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Deoxyribonucleic acid (/diˈɒksiˌraɪboʊnjʊˈkliːɪk, -ˈkleɪ.ɪk/ ( listen);[1] DNA) is a thread-like chain of nucleotides carrying the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses. DNA
DNA
and ribonucleic acid (RNA) are nucleic acids; alongside proteins, lipids and complex carbohydrates (polysaccharides), they are one of the four major types of macromolecules that are essential for all known forms of life. Most DNA
DNA
molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA
DNA
strands are called polynucleotides since they are composed of simpler monomer units called nucleotides.[2][3] Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two separate polynucleotide strands are bound together, according to base pairing rules (A with T and C with G), with hydrogen bonds to make double-stranded DNA. The complementary nitrogenous bases are divided into two groups, pyrimidines and purines. In a DNA
DNA
molecule, the pyrimidines are thymine and cytosine, the purines are adenine and guanine. DNA
DNA
stores biological information. The DNA
DNA
backbone is resistant to cleavage, and both strands of the double-stranded structure store the same biological information. This information is replicated as and when the two strands separate. A large part of DNA
DNA
(more than 98% for humans) is non-coding, meaning that these sections do not serve as patterns for protein sequences. The two strands of DNA
DNA
run in opposite directions to each other and are thus antiparallel. Attached to each sugar is one of four types of nucleobases (informally, bases). It is the sequence of these four nucleobases along the backbone that encodes biological information. RNA
RNA
strands are created using DNA
DNA
strands as a template in a process called transcription. Under the genetic code, these RNA
RNA
strands are translated to specify the sequence of amino acids within proteins in a process called translation. Within eukaryotic cells DNA
DNA
is organized into long structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA
DNA
replication, providing each cell its own complete set of chromosomes. Eukaryotic organisms (animals, plants, fungi and protists) store most of their DNA
DNA
inside the cell nucleus and some of their DNA
DNA
in organelles, such as mitochondria or chloroplasts.[4] In contrast prokaryotes (bacteria and archaea) store their DNA
DNA
only in the cytoplasm. Within the eukaryotic chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA
DNA
and other proteins, helping control which parts of the DNA
DNA
are transcribed. DNA
DNA
was first isolated by Friedrich Miescher
Friedrich Miescher
in 1869. Its molecular structure was first identified by James Watson
James Watson
and Francis Crick
Francis Crick
at the Cavendish Laboratory
Cavendish Laboratory
within the University of Cambridge
University of Cambridge
in 1953, whose model-building efforts were guided by X-ray diffraction
X-ray diffraction
data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin. DNA
DNA
is used by researchers as a molecular tool to explore physical laws and theories, such as the ergodic theorem and the theory of elasticity. The unique material properties of DNA
DNA
have made it an attractive molecule for material scientists and engineers interested in micro- and nano-fabrication. Among notable advances in this field are DNA origami
DNA origami
and DNA-based hybrid materials.[5]

Contents

1 Properties

1.1 Nucleobase
Nucleobase
classification 1.2 Non canonical bases 1.3 Listing of non canonical bases found in DNA 1.4 Grooves 1.5 Base pairing 1.6 Sense and antisense 1.7 Supercoiling 1.8 Alternative DNA
DNA
structures 1.9 Alternative DNA
DNA
chemistry 1.10 Quadruplex structures 1.11 Branched DNA

2 Chemical modifications and altered DNA
DNA
packaging

2.1 Base modifications and DNA
DNA
packaging 2.2 Damage

3 Biological functions

3.1 Genes and genomes 3.2 Transcription and translation 3.3 Replication 3.4 Extracellular nucleic acids

4 Interactions with proteins

4.1 DNA-binding proteins 4.2 DNA-modifying enzymes

4.2.1 Nucleases and ligases 4.2.2 Topoisomerases and helicases 4.2.3 Polymerases

5 Genetic recombination 6 Evolution 7 Uses in technology

7.1 Genetic engineering 7.2 DNA
DNA
profiling 7.3 DNA
DNA
enzymes or catalytic DNA 7.4 Bioinformatics 7.5 DNA
DNA
nanotechnology 7.6 History and anthropology 7.7 Information
Information
storage

8 History of DNA
DNA
research 9 See also 10 References 11 Further reading 12 External links

Properties

Chemical structure of DNA; hydrogen bonds shown as dotted lines

DNA
DNA
is a long polymer made from repeating units called nucleotides.[6][7] The structure of DNA
DNA
is dynamic along its length, being capable of coiling into tight loops, and other shapes.[8] In all species it is composed of two helical chains, bound to each other by hydrogen bonds. Both chains are coiled round the same axis, and have the same pitch of 34 ångströms (3.4 nanometres). The pair of chains has a radius of 10 ångströms (1.0 nanometre).[9] According to another study, when measured in a different solution, the DNA
DNA
chain measured 22 to 26 ångströms wide (2.2 to 2.6 nanometres), and one nucleotide unit measured 3.3 Å (0.33 nm) long.[10] Although each individual nucleotide repeating unit is very small, DNA
DNA
polymers can be very large molecules containing millions to hundreds of millions of nucleotides. For instance, the DNA
DNA
in the largest human chromosome, chromosome number 1, consists of approximately 220 million base pairs[11] and would be 85 mm long if straightened. In living organisms, DNA
DNA
does not usually exist as a single molecule, but instead as a pair of molecules that are held tightly together.[12][13] These two long strands entwine like vines, in the shape of a double helix. The nucleotide contains both a segment of the backbone of the molecule (which holds the chain together) and a nucleobase (which interacts with the other DNA
DNA
strand in the helix). A nucleobase linked to a sugar is called a nucleoside and a base linked to a sugar and one or more phosphate groups is called a nucleotide. A polymer comprising multiple linked nucleotides (as in DNA) is called a polynucleotide.[14] The backbone of the DNA
DNA
strand is made from alternating phosphate and sugar residues.[15] The sugar in DNA
DNA
is 2-deoxyribose, which is a pentose (five-carbon) sugar. The sugars are joined together by phosphate groups that form phosphodiester bonds between the third and fifth carbon atoms of adjacent sugar rings. These asymmetric bonds mean a strand of DNA
DNA
has a direction. In a double helix, the direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel. The asymmetric ends of DNA strands are said to have a directionality of five prime (5′) and three prime (3′), with the 5′ end having a terminal phosphate group and the 3′ end a terminal hydroxyl group. One major difference between DNA
DNA
and RNA
RNA
is the sugar, with the 2-deoxyribose in DNA
DNA
being replaced by the alternative pentose sugar ribose in RNA.[13]

A section of DNA. The bases lie horizontally between the two spiraling strands.[16] (animated version).

The DNA
DNA
double helix is stabilized primarily by two forces: hydrogen bonds between nucleotides and base-stacking interactions among aromatic nucleobases.[17] In the aqueous environment of the cell, the conjugated π bonds of nucleotide bases align perpendicular to the axis of the DNA
DNA
molecule, minimizing their interaction with the solvation shell. The four bases found in DNA
DNA
are adenine (A), cytosine (C), guanine (G) and thymine (T). These four bases are attached to the sugar-phosphate to form the complete nucleotide, as shown for adenosine monophosphate. Adenine
Adenine
pairs with thymine and guanine pairs with cytosine. It was represented by A-T base pairs and G-C base pairs.[18][19] Nucleobase
Nucleobase
classification The nucleobases are classified into two types: the purines, A and G, being fused five- and six-membered heterocyclic compounds, and the pyrimidines, the six-membered rings C and T.[13] A fifth pyrimidine nucleobase, uracil (U), usually takes the place of thymine in RNA
RNA
and differs from thymine by lacking a methyl group on its ring. In addition to RNA
RNA
and DNA, many artificial nucleic acid analogues have been created to study the properties of nucleic acids, or for use in biotechnology.[20] Non canonical bases Uracil
Uracil
is not usually found in DNA, occurring only as a breakdown product of cytosine. However, in several bacteriophages, Bacillus subtilis bacteriophages PBS1 and PBS2 and Yersinia bacteriophage piR1-37, thymine has been replaced by uracil.[21] Another phage - Staphylococcal phage S6 - has been identified with a genome where thymine has been replaced by uracil.[22] 5-hydroxymethyldeoxyuracil (hm5dU) is also known to replace thymidine in several genomes including the Bacillus phages SPO1, ϕe, SP8, H1, 2C and SP82. Another modified uracil - 5-dihydroxypentauracil – has also been described.[23] Base J
Base J
(beta-d-glucopyranosyloxymethyluracil), a modified form of uracil, is also found in several organisms: the flagellates Diplonema and Euglena, and all the kinetoplastid genera.[24] Biosynthesis
Biosynthesis
of J occurs in two steps: in the first step, a specific thymidine in DNA
DNA
is converted into hydroxymethyldeoxyuridine; in the second, HOMedU is glycosylated to form J.[25] Proteins that bind specifically to this base have been identified.[26][27][28] These proteins appear to be distant relatives of the Tet1 oncogene that is involved in the pathogenesis of acute myeloid leukemia.[29] J appears to act as a termination signal for RNA
RNA
polymerase II.[30][31] In 1976 a bacteriophage - S-2L - which infects species of the genus Synechocystis was found to have all the adenosine bases within its genome replaced by 2,6-diaminopurine.[32] In 2016 deoxyarchaeosine was found to be present in the genomes of several bacteria and the Escherichia
Escherichia
phage 9g.[33] Modified bases also occur in DNA. The first of these recognised was 5-methylcytosine which was found in the genome of Mycobacterium tuberculosis in 1925.[34] The complete replacement of cytosine by 5-glycosylhydroxymethylcytosine in T even phages (T2, T4 and T6) was observed in 1953[35] In the genomes of Xanthomonas oryzae bacteriophage Xp12 and halovirus FH the full complement of cystosine has been replaced by 5-methylcytosine.[36][37] 6N-methyadenine was discovered to be present in DNA
DNA
in 1955.[38] N6-carbamoyl-methyladenine was described in 1975.[39] 7-methylguanine was described in 1976.[40] N4-methylcytosine in DNA
DNA
was described in 1983.[41] In 1985 5-hydroxycytosine was found in the genomes of the Rhizobium
Rhizobium
phages RL38JI and N17.[42] α-putrescinylthymine occurs in both the genomes of the Delftia phage ΦW-14 and the Bacillus phage SP10.[43] α-glutamythymidine is found in the Bacillus phage SP01 and 5-dihydroxypentyluracil is found in the Bacillus phage SP15. The reason for the presence of these non canonical bases in DNA
DNA
is not known. It seems likely that at least part of the reason for their presence in bacterial viruses (phages) is to avoid the restriction enzymes present in bacteria. This enzyme system acts at least in part as a molecular immune system protecting bacteria from infection by viruses. This does not appear to be the entire story. Four modifications to the cytosine residues in human DNA
DNA
have been reported.[44] These modifications are the addition of methyl (CH3)-, hydroxymethyl (CH2OH)-, formyl (CHO)- and carboxyl (COOH)- groups. These modifications are thought to have regulatory functions. Listing of non canonical bases found in DNA Seventeen non canonical bases are known to occur in DNA. Most of these are modifications of the canonical bases plus uracil.

Modified Adenosine

N6-carbamoyl-methyladenine N6-methyadenine

Modified Guanine

7-Methylguanine

Modified Cytosine

N4-Methylcytosine 5-Carboxylcytosine 5-Formylcytosine 5-Glycosylhydroxymethylcytosine 5-Hydroxycytosine 5-Methylcytosine

Modified Thymidine

α-Glutamythymidine α-Putrescinylthymine

Uracil
Uracil
and modifications

Base J Uracil 5-Dihydroxypentauracil 5-Hydroxymethyldeoxyuracil

Others

Deoxyarchaeosine 2,6-Diaminopurine

DNA
DNA
major and minor grooves. The latter is a binding site for the Hoechst stain
Hoechst stain
dye 33258.

Grooves Twin helical strands form the DNA
DNA
backbone. Another double helix may be found tracing the spaces, or grooves, between the strands. These voids are adjacent to the base pairs and may provide a binding site. As the strands are not symmetrically located with respect to each other, the grooves are unequally sized. One groove, the major groove, is 22 Å wide and the other, the minor groove, is 12 Å wide.[45] The width of the major groove means that the edges of the bases are more accessible in the major groove than in the minor groove. As a result, proteins such as transcription factors that can bind to specific sequences in double-stranded DNA
DNA
usually make contact with the sides of the bases exposed in the major groove.[46] This situation varies in unusual conformations of DNA
DNA
within the cell (see below), but the major and minor grooves are always named to reflect the differences in size that would be seen if the DNA
DNA
is twisted back into the ordinary B form. Base pairing Further information: Base pair In a DNA
DNA
double helix, each type of nucleobase on one strand bonds with just one type of nucleobase on the other strand. This is called complementary base pairing. Here, purines form hydrogen bonds to pyrimidines, with adenine bonding only to thymine in two hydrogen bonds, and cytosine bonding only to guanine in three hydrogen bonds. This arrangement of two nucleotides binding together across the double helix is called a Watson-Crick base pair. Another type of base pairing is Hoogsteen base pairing where two hydrogen bonds form between guanine and cytosine.[47] As hydrogen bonds are not covalent, they can be broken and rejoined relatively easily. The two strands of DNA
DNA
in a double helix can thus be pulled apart like a zipper, either by a mechanical force or high temperature.[48] As a result of this base pair complementarity, all the information in the double-stranded sequence of a DNA
DNA
helix is duplicated on each strand, which is vital in DNA
DNA
replication. This reversible and specific interaction between complementary base pairs is critical for all the functions of DNA
DNA
in living organisms.[7]

Top, a GC base pair with three hydrogen bonds. Bottom, an AT base pair with two hydrogen bonds. Non-covalent hydrogen bonds between the pairs are shown as dashed lines.

The two types of base pairs form different numbers of hydrogen bonds, AT forming two hydrogen bonds, and GC forming three hydrogen bonds (see figures, right). DNA
DNA
with high GC-content
GC-content
is more stable than DNA with low GC-content. As noted above, most DNA
DNA
molecules are actually two polymer strands, bound together in a helical fashion by noncovalent bonds; this double-stranded (dsDNA) structure is maintained largely by the intrastrand base stacking interactions, which are strongest for G,C stacks. The two strands can come apart – a process known as melting – to form two single-stranded DNA
DNA
(ssDNA) molecules. Melting occurs at high temperature, low salt and high pH (low pH also melts DNA, but since DNA
DNA
is unstable due to acid depurination, low pH is rarely used). The stability of the ds DNA
DNA
form depends not only on the GC-content
GC-content
(% G,C basepairs) but also on sequence (since stacking is sequence specific) and also length (longer molecules are more stable). The stability can be measured in various ways; a common way is the "melting temperature", which is the temperature at which 50% of the ds molecules are converted to ss molecules; melting temperature is dependent on ionic strength and the concentration of DNA. As a result, it is both the percentage of GC base pairs and the overall length of a DNA
DNA
double helix that determines the strength of the association between the two strands of DNA. Long DNA
DNA
helices with a high GC-content
GC-content
have stronger-interacting strands, while short helices with high AT content have weaker-interacting strands.[49] In biology, parts of the DNA
DNA
double helix that need to separate easily, such as the TATAAT Pribnow box in some promoters, tend to have a high AT content, making the strands easier to pull apart.[50] In the laboratory, the strength of this interaction can be measured by finding the temperature necessary to break the hydrogen bonds, their melting temperature (also called Tm value). When all the base pairs in a DNA
DNA
double helix melt, the strands separate and exist in solution as two entirely independent molecules. These single-stranded DNA molecules have no single common shape, but some conformations are more stable than others.[51] Sense and antisense Further information: Sense (molecular biology) A DNA sequence
DNA sequence
is called "sense" if its sequence is the same as that of a messenger RNA
RNA
copy that is translated into protein.[52] The sequence on the opposite strand is called the "antisense" sequence. Both sense and antisense sequences can exist on different parts of the same strand of DNA
DNA
(i.e. both strands can contain both sense and antisense sequences). In both prokaryotes and eukaryotes, antisense RNA
RNA
sequences are produced, but the functions of these RNAs are not entirely clear.[53] One proposal is that antisense RNAs are involved in regulating gene expression through RNA- RNA
RNA
base pairing.[54] A few DNA
DNA
sequences in prokaryotes and eukaryotes, and more in plasmids and viruses, blur the distinction between sense and antisense strands by having overlapping genes.[55] In these cases, some DNA sequences do double duty, encoding one protein when read along one strand, and a second protein when read in the opposite direction along the other strand. In bacteria, this overlap may be involved in the regulation of gene transcription,[56] while in viruses, overlapping genes increase the amount of information that can be encoded within the small viral genome.[57] Supercoiling Further information: DNA
DNA
supercoil DNA
DNA
can be twisted like a rope in a process called DNA
DNA
supercoiling. With DNA
DNA
in its "relaxed" state, a strand usually circles the axis of the double helix once every 10.4 base pairs, but if the DNA
DNA
is twisted the strands become more tightly or more loosely wound.[58] If the DNA is twisted in the direction of the helix, this is positive supercoiling, and the bases are held more tightly together. If they are twisted in the opposite direction, this is negative supercoiling, and the bases come apart more easily. In nature, most DNA
DNA
has slight negative supercoiling that is introduced by enzymes called topoisomerases.[59] These enzymes are also needed to relieve the twisting stresses introduced into DNA
DNA
strands during processes such as transcription and DNA
DNA
replication.[60]

From left to right, the structures of A, B and Z DNA

Alternative DNA
DNA
structures Further information: Molecular Structure of Nucleic Acids: A Structure for Deoxyribose
Deoxyribose
Nucleic Acid, Molecular models of DNA, and DNA structure DNA
DNA
exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA
Z-DNA
forms, although, only B- DNA
DNA
and Z-DNA
Z-DNA
have been directly observed in functional organisms.[15] The conformation that DNA
DNA
adopts depends on the hydration level, DNA
DNA
sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and concentration of metal ions, and the presence of polyamines in solution.[61] The first published reports of A-DNA
A-DNA
X-ray diffraction
X-ray diffraction
patterns—and also B-DNA—used analyses based on Patterson transforms that provided only a limited amount of structural information for oriented fibers of DNA.[62][63] An alternative analysis was then proposed by Wilkins et al., in 1953, for the in vivo B- DNA
DNA
X-ray
X-ray
diffraction-scattering patterns of highly hydrated DNA
DNA
fibers in terms of squares of Bessel functions.[64] In the same journal, James Watson
James Watson
and Francis Crick presented their molecular modeling analysis of the DNA
DNA
X-ray diffraction patterns to suggest that the structure was a double-helix.[9] Although the B- DNA
DNA
form is most common under the conditions found in cells,[65] it is not a well-defined conformation but a family of related DNA
DNA
conformations[66] that occur at the high hydration levels present in living cells. Their corresponding X-ray diffraction
X-ray diffraction
and scattering patterns are characteristic of molecular paracrystals with a significant degree of disorder.[67][68] Compared to B-DNA, the A-DNA
A-DNA
form is a wider right-handed spiral, with a shallow, wide minor groove and a narrower, deeper major groove. The A form occurs under non-physiological conditions in partly dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA
DNA
and RNA
RNA
strands, and in enzyme- DNA
DNA
complexes.[69][70] Segments of DNA
DNA
where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt the Z form. Here, the strands turn about the helical axis in a left-handed spiral, the opposite of the more common B form.[71] These unusual structures can be recognized by specific Z-DNA
Z-DNA
binding proteins and may be involved in the regulation of transcription.[72] Alternative DNA
DNA
chemistry For many years exobiologists have proposed the existence of a shadow biosphere, a postulated microbial biosphere of Earth that uses radically different biochemical and molecular processes than currently known life. One of the proposals was the existence of lifeforms that use arsenic instead of phosphorus in DNA. A report in 2010 of the possibility in the bacterium GFAJ-1, was announced,[73][73][74] though the research was disputed,[74][75] and evidence suggests the bacterium actively prevents the incorporation of arsenic into the DNA
DNA
backbone and other biomolecules.[76] Quadruplex structures Further information: G-quadruplex At the ends of the linear chromosomes are specialized regions of DNA called telomeres. The main function of these regions is to allow the cell to replicate chromosome ends using the enzyme telomerase, as the enzymes that normally replicate DNA
DNA
cannot copy the extreme 3′ ends of chromosomes.[77] These specialized chromosome caps also help protect the DNA
DNA
ends, and stop the DNA repair
DNA repair
systems in the cell from treating them as damage to be corrected.[78] In human cells, telomeres are usually lengths of single-stranded DNA
DNA
containing several thousand repeats of a simple TTAGGG sequence.[79]

DNA
DNA
quadruplex formed by telomere repeats. The looped conformation of the DNA
DNA
backbone is very different from the typical DNA
DNA
helix. The green spheres in the center represent potassium ions.[80]

These guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units, rather than the usual base pairs found in other DNA
DNA
molecules. Here, four guanine bases form a flat plate and these flat four-base units then stack on top of each other, to form a stable G-quadruplex
G-quadruplex
structure.[81] These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit.[82] Other structures can also be formed, with the central set of four bases coming from either a single strand folded around the bases, or several different parallel strands, each contributing one base to the central structure. In addition to these stacked structures, telomeres also form large loop structures called telomere loops, or T-loops. Here, the single-stranded DNA
DNA
curls around in a long circle stabilized by telomere-binding proteins.[83] At the very end of the T-loop, the single-stranded telomere DNA
DNA
is held onto a region of double-stranded DNA
DNA
by the telomere strand disrupting the double-helical DNA
DNA
and base pairing to one of the two strands. This triple-stranded structure is called a displacement loop or D-loop.[81]

Single branch Multiple branches

Branched DNA can form networks containing multiple branches.

Branched DNA Further information: Branched DNA and DNA
DNA
nanotechnology In DNA, fraying occurs when non-complementary regions exist at the end of an otherwise complementary double-strand of DNA. However, branched DNA
DNA
can occur if a third strand of DNA
DNA
is introduced and contains adjoining regions able to hybridize with the frayed regions of the pre-existing double-strand. Although the simplest example of branched DNA
DNA
involves only three strands of DNA, complexes involving additional strands and multiple branches are also possible.[84] Branched DNA can be used in nanotechnology to construct geometric shapes, see the section on uses in technology below. Chemical modifications and altered DNA
DNA
packaging

cytosine 5-methylcytosine thymine

Structure of cytosine with and without the 5-methyl group. Deamination converts 5-methylcytosine into thymine.

Base modifications and DNA
DNA
packaging Further information: DNA methylation
DNA methylation
and Chromatin
Chromatin
remodeling The expression of genes is influenced by how the DNA
DNA
is packaged in chromosomes, in a structure called chromatin. Base modifications can be involved in packaging, with regions that have low or no gene expression usually containing high levels of methylation of cytosine bases. DNA
DNA
packaging and its influence on gene expression can also occur by covalent modifications of the histone protein core around which DNA
DNA
is wrapped in the chromatin structure or else by remodeling carried out by chromatin remodeling complexes (see Chromatin remodeling). There is, further, crosstalk between DNA methylation
DNA methylation
and histone modification, so they can coordinately affect chromatin and gene expression.[85] For one example, cytosine methylation produces 5-methylcytosine, which is important for X-inactivation
X-inactivation
of chromosomes.[86] The average level of methylation varies between organisms – the worm Caenorhabditis elegans
Caenorhabditis elegans
lacks cytosine methylation, while vertebrates have higher levels, with up to 1% of their DNA
DNA
containing 5-methylcytosine.[87] Despite the importance of 5-methylcytosine, it can deaminate to leave a thymine base, so methylated cytosines are particularly prone to mutations.[88] Other base modifications include adenine methylation in bacteria, the presence of 5-hydroxymethylcytosine
5-hydroxymethylcytosine
in the brain,[89] and the glycosylation of uracil to produce the "J-base" in kinetoplastids.[90][91] Damage Further information: DNA
DNA
damage (naturally occurring), Mutation, and DNA
DNA
damage theory of aging

A covalent adduct between a metabolically activated form of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA[92]

DNA
DNA
can be damaged by many sorts of mutagens, which change the DNA sequence. Mutagens include oxidizing agents, alkylating agents and also high-energy electromagnetic radiation such as ultraviolet light and X-rays. The type of DNA
DNA
damage produced depends on the type of mutagen. For example, UV light can damage DNA
DNA
by producing thymine dimers, which are cross-links between pyrimidine bases.[93] On the other hand, oxidants such as free radicals or hydrogen peroxide produce multiple forms of damage, including base modifications, particularly of guanosine, and double-strand breaks.[94] A typical human cell contains about 150,000 bases that have suffered oxidative damage.[95] Of these oxidative lesions, the most dangerous are double-strand breaks, as these are difficult to repair and can produce point mutations, insertions, deletions from the DNA
DNA
sequence, and chromosomal translocations.[96] These mutations can cause cancer. Because of inherent limits in the DNA repair
DNA repair
mechanisms, if humans lived long enough, they would all eventually develop cancer.[97][98] DNA
DNA
damages that are naturally occurring, due to normal cellular processes that produce reactive oxygen species, the hydrolytic activities of cellular water, etc., also occur frequently. Although most of these damages are repaired, in any cell some DNA
DNA
damage may remain despite the action of repair processes. These remaining DNA damages accumulate with age in mammalian postmitotic tissues. This accumulation appears to be an important underlying cause of aging.[99][100][101] Many mutagens fit into the space between two adjacent base pairs, this is called intercalation. Most intercalators are aromatic and planar molecules; examples include ethidium bromide, acridines, daunomycin, and doxorubicin. For an intercalator to fit between base pairs, the bases must separate, distorting the DNA
DNA
strands by unwinding of the double helix. This inhibits both transcription and DNA
DNA
replication, causing toxicity and mutations.[102] As a result, DNA
DNA
intercalators may be carcinogens, and in the case of thalidomide, a teratogen.[103] Others such as benzo[a]pyrene diol epoxide and aflatoxin form DNA adducts that induce errors in replication.[104] Nevertheless, due to their ability to inhibit DNA
DNA
transcription and replication, other similar toxins are also used in chemotherapy to inhibit rapidly growing cancer cells.[105] Biological functions

Location of eukaryote nuclear DNA
DNA
within the chromosomes.

DNA
DNA
usually occurs as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes. The set of chromosomes in a cell makes up its genome; the human genome has approximately 3 billion base pairs of DNA
DNA
arranged into 46 chromosomes.[106] The information carried by DNA is held in the sequence of pieces of DNA
DNA
called genes. Transmission of genetic information in genes is achieved via complementary base pairing. For example, in transcription, when a cell uses the information in a gene, the DNA sequence
DNA sequence
is copied into a complementary RNA
RNA
sequence through the attraction between the DNA
DNA
and the correct RNA
RNA
nucleotides. Usually, this RNA
RNA
copy is then used to make a matching protein sequence in a process called translation, which depends on the same interaction between RNA
RNA
nucleotides. In alternative fashion, a cell may simply copy its genetic information in a process called DNA
DNA
replication. The details of these functions are covered in other articles; here the focus is on the interactions between DNA
DNA
and other molecules that mediate the function of the genome. Genes and genomes Further information: Cell nucleus, Chromatin, Chromosome, Gene, and Noncoding DNA Genomic DNA is tightly and orderly packed in the process called DNA condensation, to fit the small available volumes of the cell. In eukaryotes, DNA
DNA
is located in the cell nucleus, with small amounts in mitochondria and chloroplasts. In prokaryotes, the DNA
DNA
is held within an irregularly shaped body in the cytoplasm called the nucleoid.[107] The genetic information in a genome is held within genes, and the complete set of this information in an organism is called its genotype. A gene is a unit of heredity and is a region of DNA
DNA
that influences a particular characteristic in an organism. Genes contain an open reading frame that can be transcribed, and regulatory sequences such as promoters and enhancers, which control transcription of the open reading frame. In many species, only a small fraction of the total sequence of the genome encodes protein. For example, only about 1.5% of the human genome consists of protein-coding exons, with over 50% of human DNA consisting of non-coding repetitive sequences.[108] The reasons for the presence of so much noncoding DNA
DNA
in eukaryotic genomes and the extraordinary differences in genome size, or C-value, among species, represent a long-standing puzzle known as the " C-value enigma".[109] However, some DNA
DNA
sequences that do not code protein may still encode functional non-coding RNA
RNA
molecules, which are involved in the regulation of gene expression.[110]

T7 RNA
RNA
polymerase (blue) producing an m RNA
RNA
(green) from a DNA
DNA
template (orange).[111]

Some noncoding DNA
DNA
sequences play structural roles in chromosomes. Telomeres
Telomeres
and centromeres typically contain few genes but are important for the function and stability of chromosomes.[78][112] An abundant form of noncoding DNA
DNA
in humans are pseudogenes, which are copies of genes that have been disabled by mutation.[113] These sequences are usually just molecular fossils, although they can occasionally serve as raw genetic material for the creation of new genes through the process of gene duplication and divergence.[114] Transcription and translation Further information: Genetic code, Transcription (genetics), and Protein
Protein
biosynthesis A gene is a sequence of DNA
DNA
that contains genetic information and can influence the phenotype of an organism. Within a gene, the sequence of bases along a DNA
DNA
strand defines a messenger RNA
RNA
sequence, which then defines one or more protein sequences. The relationship between the nucleotide sequences of genes and the amino-acid sequences of proteins is determined by the rules of translation, known collectively as the genetic code. The genetic code consists of three-letter 'words' called codons formed from a sequence of three nucleotides (e.g. ACT, CAG, TTT). In transcription, the codons of a gene are copied into messenger RNA by RNA
RNA
polymerase. This RNA
RNA
copy is then decoded by a ribosome that reads the RNA
RNA
sequence by base-pairing the messenger RNA
RNA
to transfer RNA, which carries amino acids. Since there are 4 bases in 3-letter combinations, there are 64 possible codons (43 combinations). These encode the twenty standard amino acids, giving most amino acids more than one possible codon. There are also three 'stop' or 'nonsense' codons signifying the end of the coding region; these are the TAA, TGA, and TAG codons.

DNA
DNA
replication. The double helix is unwound by a helicase and topoisomerase. Next, one DNA polymerase
DNA polymerase
produces the leading strand copy. Another DNA polymerase
DNA polymerase
binds to the lagging strand. This enzyme makes discontinuous segments (called Okazaki fragments) before DNA ligase joins them together.

Replication Further information: DNA
DNA
replication Cell division
Cell division
is essential for an organism to grow, but, when a cell divides, it must replicate the DNA
DNA
in its genome so that the two daughter cells have the same genetic information as their parent. The double-stranded structure of DNA
DNA
provides a simple mechanism for DNA replication. Here, the two strands are separated and then each strand's complementary DNA sequence
DNA sequence
is recreated by an enzyme called DNA
DNA
polymerase. This enzyme makes the complementary strand by finding the correct base through complementary base pairing and bonding it onto the original strand. As DNA
DNA
polymerases can only extend a DNA strand in a 5′ to 3′ direction, different mechanisms are used to copy the antiparallel strands of the double helix.[115] In this way, the base on the old strand dictates which base appears on the new strand, and the cell ends up with a perfect copy of its DNA. Extracellular nucleic acids Naked extracellular DNA
DNA
(eDNA), most of it released by cell death, is nearly ubiquitous in the environment. Its concentration in soil may be as high as 2 μg/L, and its concentration in natural aquatic environments may be as high at 88 μg/L.[116] Various possible functions have been proposed for eDNA: it may be involved in horizontal gene transfer;[117] it may provide nutrients;[118] and it may act as a buffer to recruit or titrate ions or antibiotics.[119] Extracellular DNA
DNA
acts as a functional extracellular matrix component in the biofilms of several bacterial species. It may act as a recognition factor to regulate the attachment and dispersal of specific cell types in the biofilm;[120] it may contribute to biofilm formation;[121] and it may contribute to the biofilm's physical strength and resistance to biological stress.[122] Cell-free fetal DNA
Cell-free fetal DNA
is found in the blood of the mother, and can be sequenced to determine a great deal of information about the developing fetus.[123] Interactions with proteins All the functions of DNA
DNA
depend on interactions with proteins. These protein interactions can be non-specific, or the protein can bind specifically to a single DNA
DNA
sequence. Enzymes can also bind to DNA and of these, the polymerases that copy the DNA
DNA
base sequence in transcription and DNA replication
DNA replication
are particularly important. DNA-binding proteins Further information: DNA-binding protein

Interaction of DNA
DNA
(in orange) with histones (in blue). These proteins' basic amino acids bind to the acidic phosphate groups on DNA.

Structural proteins that bind DNA
DNA
are well-understood examples of non-specific DNA-protein interactions. Within chromosomes, DNA
DNA
is held in complexes with structural proteins. These proteins organize the DNA into a compact structure called chromatin. In eukaryotes, this structure involves DNA
DNA
binding to a complex of small basic proteins called histones, while in prokaryotes multiple types of proteins are involved.[124][125] The histones form a disk-shaped complex called a nucleosome, which contains two complete turns of double-stranded DNA wrapped around its surface. These non-specific interactions are formed through basic residues in the histones, making ionic bonds to the acidic sugar-phosphate backbone of the DNA, and are thus largely independent of the base sequence.[126] Chemical modifications of these basic amino acid residues include methylation, phosphorylation, and acetylation.[127] These chemical changes alter the strength of the interaction between the DNA
DNA
and the histones, making the DNA
DNA
more or less accessible to transcription factors and changing the rate of transcription.[128] Other non-specific DNA-binding proteins in chromatin include the high-mobility group proteins, which bind to bent or distorted DNA.[129] These proteins are important in bending arrays of nucleosomes and arranging them into the larger structures that make up chromosomes.[130] A distinct group of DNA-binding proteins is the DNA-binding proteins that specifically bind single-stranded DNA. In humans, replication protein A is the best-understood member of this family and is used in processes where the double helix is separated, including DNA replication, recombination, and DNA
DNA
repair.[131] These binding proteins seem to stabilize single-stranded DNA
DNA
and protect it from forming stem-loops or being degraded by nucleases.

The lambda repressor helix-turn-helix transcription factor bound to its DNA
DNA
target[132]

In contrast, other proteins have evolved to bind to particular DNA sequences. The most intensively studied of these are the various transcription factors, which are proteins that regulate transcription. Each transcription factor binds to one particular set of DNA
DNA
sequences and activates or inhibits the transcription of genes that have these sequences close to their promoters. The transcription factors do this in two ways. Firstly, they can bind the RNA
RNA
polymerase responsible for transcription, either directly or through other mediator proteins; this locates the polymerase at the promoter and allows it to begin transcription.[133] Alternatively, transcription factors can bind enzymes that modify the histones at the promoter. This changes the accessibility of the DNA
DNA
template to the polymerase.[134] As these DNA
DNA
targets can occur throughout an organism's genome, changes in the activity of one type of transcription factor can affect thousands of genes.[135] Consequently, these proteins are often the targets of the signal transduction processes that control responses to environmental changes or cellular differentiation and development. The specificity of these transcription factors' interactions with DNA
DNA
come from the proteins making multiple contacts to the edges of the DNA bases, allowing them to "read" the DNA
DNA
sequence. Most of these base-interactions are made in the major groove, where the bases are most accessible.[46]

The restriction enzyme EcoRV
EcoRV
(green) in a complex with its substrate DNA[136]

DNA-modifying enzymes Nucleases and ligases Nucleases are enzymes that cut DNA
DNA
strands by catalyzing the hydrolysis of the phosphodiester bonds. Nucleases that hydrolyse nucleotides from the ends of DNA
DNA
strands are called exonucleases, while endonucleases cut within strands. The most frequently used nucleases in molecular biology are the restriction endonucleases, which cut DNA
DNA
at specific sequences. For instance, the EcoRV
EcoRV
enzyme shown to the left recognizes the 6-base sequence 5′-GATATC-3′ and makes a cut at the horizontal line. In nature, these enzymes protect bacteria against phage infection by digesting the phage DNA
DNA
when it enters the bacterial cell, acting as part of the restriction modification system.[137] In technology, these sequence-specific nucleases are used in molecular cloning and DNA
DNA
fingerprinting. Enzymes called DNA
DNA
ligases can rejoin cut or broken DNA
DNA
strands.[138] Ligases are particularly important in lagging strand DNA
DNA
replication, as they join together the short segments of DNA
DNA
produced at the replication fork into a complete copy of the DNA
DNA
template. They are also used in DNA repair
DNA repair
and genetic recombination.[138] Topoisomerases and helicases Topoisomerases are enzymes with both nuclease and ligase activity. These proteins change the amount of supercoiling in DNA. Some of these enzymes work by cutting the DNA
DNA
helix and allowing one section to rotate, thereby reducing its level of supercoiling; the enzyme then seals the DNA
DNA
break.[59] Other types of these enzymes are capable of cutting one DNA
DNA
helix and then passing a second strand of DNA
DNA
through this break, before rejoining the helix.[139] Topoisomerases are required for many processes involving DNA, such as DNA replication
DNA replication
and transcription.[60] Helicases are proteins that are a type of molecular motor. They use the chemical energy in nucleoside triphosphates, predominantly adenosine triphosphate (ATP), to break hydrogen bonds between bases and unwind the DNA
DNA
double helix into single strands.[140] These enzymes are essential for most processes where enzymes need to access the DNA
DNA
bases. Polymerases Polymerases are enzymes that synthesize polynucleotide chains from nucleoside triphosphates. The sequence of their products is created based on existing polynucleotide chains—which are called templates. These enzymes function by repeatedly adding a nucleotide to the 3′ hydroxyl group at the end of the growing polynucleotide chain. As a consequence, all polymerases work in a 5′ to 3′ direction.[141] In the active site of these enzymes, the incoming nucleoside triphosphate base-pairs to the template: this allows polymerases to accurately synthesize the complementary strand of their template. Polymerases are classified according to the type of template that they use. In DNA
DNA
replication, DNA-dependent DNA
DNA
polymerases make copies of DNA polynucleotide chains. To preserve biological information, it is essential that the sequence of bases in each copy are precisely complementary to the sequence of bases in the template strand. Many DNA
DNA
polymerases have a proofreading activity. Here, the polymerase recognizes the occasional mistakes in the synthesis reaction by the lack of base pairing between the mismatched nucleotides. If a mismatch is detected, a 3′ to 5′ exonuclease activity is activated and the incorrect base removed.[142] In most organisms, DNA
DNA
polymerases function in a large complex called the replisome that contains multiple accessory subunits, such as the DNA clamp
DNA clamp
or helicases.[143] RNA-dependent DNA
DNA
polymerases are a specialized class of polymerases that copy the sequence of an RNA
RNA
strand into DNA. They include reverse transcriptase, which is a viral enzyme involved in the infection of cells by retroviruses, and telomerase, which is required for the replication of telomeres.[77][144] For example, HIV reverse transcriptase is an enzyme for AIDS virus replication.[144] Telomerase is an unusual polymerase because it contains its own RNA
RNA
template as part of its structure. It synthesizes telomeres at the ends of chromosomes. Telomeres
Telomeres
prevent fusion of the ends of neighboring chromosomes and protect chromosome ends from damage.[78] Transcription is carried out by a DNA-dependent RNA
RNA
polymerase that copies the sequence of a DNA
DNA
strand into RNA. To begin transcribing a gene, the RNA
RNA
polymerase binds to a sequence of DNA
DNA
called a promoter and separates the DNA
DNA
strands. It then copies the gene sequence into a messenger RNA
RNA
transcript until it reaches a region of DNA
DNA
called the terminator, where it halts and detaches from the DNA. As with human DNA-dependent DNA
DNA
polymerases, RNA
RNA
polymerase II, the enzyme that transcribes most of the genes in the human genome, operates as part of a large protein complex with multiple regulatory and accessory subunits.[145] Genetic recombination

Structure of the Holliday junction
Holliday junction
intermediate in genetic recombination. The four separate DNA
DNA
strands are coloured red, blue, green and yellow.[146]

Further information: Genetic recombination

Recombination involves the breaking and rejoining of two chromosomes (M and F) to produce two rearranged chromosomes (C1 and C2).

A DNA
DNA
helix usually does not interact with other segments of DNA, and in human cells, the different chromosomes even occupy separate areas in the nucleus called "chromosome territories".[147] This physical separation of different chromosomes is important for the ability of DNA
DNA
to function as a stable repository for information, as one of the few times chromosomes interact is in chromosomal crossover which occurs during sexual reproduction, when genetic recombination occurs. Chromosomal crossover
Chromosomal crossover
is when two DNA
DNA
helices break, swap a section and then rejoin. Recombination allows chromosomes to exchange genetic information and produces new combinations of genes, which increases the efficiency of natural selection and can be important in the rapid evolution of new proteins.[148] Genetic recombination
Genetic recombination
can also be involved in DNA repair, particularly in the cell's response to double-strand breaks.[149] The most common form of chromosomal crossover is homologous recombination, where the two chromosomes involved share very similar sequences. Non-homologous recombination can be damaging to cells, as it can produce chromosomal translocations and genetic abnormalities. The recombination reaction is catalyzed by enzymes known as recombinases, such as RAD51.[150] The first step in recombination is a double-stranded break caused by either an endonuclease or damage to the DNA.[151] A series of steps catalyzed in part by the recombinase then leads to joining of the two helices by at least one Holliday junction, in which a segment of a single strand in each helix is annealed to the complementary strand in the other helix. The Holliday junction is a tetrahedral junction structure that can be moved along the pair of chromosomes, swapping one strand for another. The recombination reaction is then halted by cleavage of the junction and re-ligation of the released DNA.[152] Only strands of like polarity exchange DNA
DNA
during recombination. There are two types of cleavage: east-west cleavage and north-south cleavage. The north-south cleavage nicks both strands of DNA, while the east-west cleavage has one strand of DNA
DNA
intact. The formation of a Holliday junction
Holliday junction
during recombination makes it possible for genetic diversity, genes to exchange on chromosomes, and expression of wild-type viral genomes. Evolution Further information: RNA
RNA
world hypothesis DNA
DNA
contains the genetic information that allows all modern living things to function, grow and reproduce. However, it is unclear how long in the 4-billion-year history of life DNA
DNA
has performed this function, as it has been proposed that the earliest forms of life may have used RNA
RNA
as their genetic material.[153][154] RNA
RNA
may have acted as the central part of early cell metabolism as it can both transmit genetic information and carry out catalysis as part of ribozymes.[155] This ancient RNA
RNA
world where nucleic acid would have been used for both catalysis and genetics may have influenced the evolution of the current genetic code based on four nucleotide bases. This would occur, since the number of different bases in such an organism is a trade-off between a small number of bases increasing replication accuracy and a large number of bases increasing the catalytic efficiency of ribozymes.[156] However, there is no direct evidence of ancient genetic systems, as recovery of DNA
DNA
from most fossils is impossible because DNA
DNA
survives in the environment for less than one million years, and slowly degrades into short fragments in solution.[157] Claims for older DNA
DNA
have been made, most notably a report of the isolation of a viable bacterium from a salt crystal 250 million years old,[158] but these claims are controversial.[159][160] Building blocks of DNA
DNA
(adenine, guanine, and related organic molecules) may have been formed extraterrestrially in outer space.[161][162][163] Complex DNA
DNA
and RNA
RNA
organic compounds of life, including uracil, cytosine, and thymine, have also been formed in the laboratory under conditions mimicking those found in outer space, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the universe, may have been formed in red giants or in interstellar cosmic dust and gas clouds.[164] Uses in technology Genetic engineering Further information: Molecular biology, Nucleic acid
Nucleic acid
methods, and Genetic engineering Methods have been developed to purify DNA
DNA
from organisms, such as phenol-chloroform extraction, and to manipulate it in the laboratory, such as restriction digests and the polymerase chain reaction. Modern biology and biochemistry make intensive use of these techniques in recombinant DNA
DNA
technology. Recombinant DNA
Recombinant DNA
is a man-made DNA
DNA
sequence that has been assembled from other DNA
DNA
sequences. They can be transformed into organisms in the form of plasmids or in the appropriate format, by using a viral vector.[165] The genetically modified organisms produced can be used to produce products such as recombinant proteins, used in medical research,[166] or be grown in agriculture.[167][168] DNA
DNA
profiling Further information: DNA
DNA
profiling Forensic scientists can use DNA
DNA
in blood, semen, skin, saliva or hair found at a crime scene to identify a matching DNA
DNA
of an individual, such as a perpetrator.[169] This process is formally termed DNA profiling, but may also be called "genetic fingerprinting". In DNA profiling, the lengths of variable sections of repetitive DNA, such as short tandem repeats and minisatellites, are compared between people. This method is usually an extremely reliable technique for identifying a matching DNA.[170] However, identification can be complicated if the scene is contaminated with DNA
DNA
from several people.[171] DNA
DNA
profiling was developed in 1984 by British geneticist Sir Alec Jeffreys,[172] and first used in forensic science to convict Colin Pitchfork
Colin Pitchfork
in the 1988 Enderby murders case.[173] The development of forensic science and the ability to now obtain genetic matching on minute samples of blood, skin, saliva, or hair has led to re-examining many cases. Evidence can now be uncovered that was scientifically impossible at the time of the original examination. Combined with the removal of the double jeopardy law in some places, this can allow cases to be reopened where prior trials have failed to produce sufficient evidence to convince a jury. People charged with serious crimes may be required to provide a sample of DNA
DNA
for matching purposes. The most obvious defense to DNA
DNA
matches obtained forensically is to claim that cross-contamination of evidence has occurred. This has resulted in meticulous strict handling procedures with new cases of serious crime. DNA profiling
DNA profiling
is also used successfully to positively identify victims of mass casualty incidents,[174] bodies or body parts in serious accidents, and individual victims in mass war graves, via matching to family members. DNA profiling
DNA profiling
is also used in DNA paternity testing
DNA paternity testing
to determine if someone is the biological parent or grandparent of a child with the probability of parentage is typically 99.99% when the alleged parent is biologically related to the child. Normal DNA sequencing
DNA sequencing
methods happen after birth, but there are new methods to test paternity while a mother is still pregnant.[175] DNA
DNA
enzymes or catalytic DNA Further information: Deoxyribozyme Deoxyribozymes, also called DNAzymes or catalytic DNA, are first discovered in 1994.[176] They are mostly single stranded DNA
DNA
sequences isolated from a large pool of random DNA
DNA
sequences through a combinatorial approach called in vitro selection or systematic evolution of ligands by exponential enrichment (SELEX). DNAzymes catalyze variety of chemical reactions including RN A-DNA
A-DNA
cleavage, RN A-DNA
A-DNA
ligation, amino acids phosphorylation-dephosphorylation, carbon-carbon bond formation, and etc. DNAzymes can enhance catalytic rate of chemical reactions up to 100,000,000,000-fold over the uncatalyzed reaction.[177] The most extensively studied class of DNAzymes is RNA-cleaving types which have been used to detect different metal ions and designing therapeutic agents. Several metal-specific DNAzymes have been reported including the GR-5 DNAzyme (lead-specific),[176] the CA1-3 DNAzymes (copper-specific),[178] the 39E DNAzyme (uranyl-specific) and the NaA43 DNAzyme (sodium-specific).[179] The NaA43 DNAzyme, which is reported to be more than 10,000-fold selective for sodium over other metal ions, was used to make a real-time sodium sensor in living cells. Bioinformatics Further information: Bioinformatics Bioinformatics
Bioinformatics
involves the development of techniques to store, data mine, search and manipulate biological data, including DNA
DNA
nucleic acid sequence data. These have led to widely applied advances in computer science, especially string searching algorithms, machine learning, and database theory.[180] String searching or matching algorithms, which find an occurrence of a sequence of letters inside a larger sequence of letters, were developed to search for specific sequences of nucleotides.[181] The DNA sequence
DNA sequence
may be aligned with other DNA
DNA
sequences to identify homologous sequences and locate the specific mutations that make them distinct. These techniques, especially multiple sequence alignment, are used in studying phylogenetic relationships and protein function.[182] Data sets representing entire genomes' worth of DNA
DNA
sequences, such as those produced by the Human Genome
Genome
Project, are difficult to use without the annotations that identify the locations of genes and regulatory elements on each chromosome. Regions of DNA sequence
DNA sequence
that have the characteristic patterns associated with protein- or RNA-coding genes can be identified by gene finding algorithms, which allow researchers to predict the presence of particular gene products and their possible functions in an organism even before they have been isolated experimentally.[183] Entire genomes may also be compared, which can shed light on the evolutionary history of particular organism and permit the examination of complex evolutionary events. DNA
DNA
nanotechnology

The DNA structure
DNA structure
at left (schematic shown) will self-assemble into the structure visualized by atomic force microscopy at right. DNA nanotechnology is the field that seeks to design nanoscale structures using the molecular recognition properties of DNA
DNA
molecules. Image from Strong, 2004.

Further information: DNA
DNA
nanotechnology DNA nanotechnology
DNA nanotechnology
uses the unique molecular recognition properties of DNA
DNA
and other nucleic acids to create self-assembling branched DNA complexes with useful properties.[184] DNA
DNA
is thus used as a structural material rather than as a carrier of biological information. This has led to the creation of two-dimensional periodic lattices (both tile-based and using the DNA origami
DNA origami
method) and three-dimensional structures in the shapes of polyhedra.[185] Nanomechanical devices and algorithmic self-assembly have also been demonstrated,[186] and these DNA
DNA
structures have been used to template the arrangement of other molecules such as gold nanoparticles and streptavidin proteins.[187] History and anthropology Further information: Phylogenetics
Phylogenetics
and Genetic genealogy Because DNA
DNA
collects mutations over time, which are then inherited, it contains historical information, and, by comparing DNA
DNA
sequences, geneticists can infer the evolutionary history of organisms, their phylogeny.[188] This field of phylogenetics is a powerful tool in evolutionary biology. If DNA
DNA
sequences within a species are compared, population geneticists can learn the history of particular populations. This can be used in studies ranging from ecological genetics to anthropology; For example, DNA
DNA
evidence is being used to try to identify the Ten Lost Tribes
Ten Lost Tribes
of Israel.[189][190] Information
Information
storage Main article: DNA
DNA
digital data storage In a paper published in Nature in January 2013, scientists from the European Bioinformatics
Bioinformatics
Institute and Agilent Technologies
Agilent Technologies
proposed a mechanism to use DNA's ability to code information as a means of digital data storage. The group was able to encode 739 kilobytes of data into DNA
DNA
code, synthesize the actual DNA, then sequence the DNA and decode the information back to its original form, with a reported 100% accuracy. The encoded information consisted of text files and audio files. A prior experiment was published in August 2012. It was conducted by researchers at Harvard University, where the text of a 54,000-word book was encoded in DNA.[191][192] Moreover, in living cells, the storage can be turned active by enzymes. Light-gated protein domains fused to DNA
DNA
processing enzymes are suitable for that task in vitro.[193][194] Fluorescent exonucleases can transmit the output according to the nucleotide they have read.[195] History of DNA
DNA
research Further information: History of molecular biology

James Watson
James Watson
and Francis Crick
Francis Crick
(right), co-originators of the double-helix model, with Maclyn McCarty
Maclyn McCarty
(left).

Pencil sketch of the DNA
DNA
double helix by Francis Crick
Francis Crick
in 1953

DNA
DNA
was first isolated by the Swiss physician Friedrich Miescher
Friedrich Miescher
who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein".[196][197] In 1878, Albrecht Kossel
Albrecht Kossel
isolated the non-protein component of "nuclein", nucleic acid, and later isolated its five primary nucleobases.[198][199] In 1919, Phoebus Levene identified the base, sugar, and phosphate nucleotide unit.[200] Levene suggested that DNA
DNA
consisted of a string of nucleotide units linked together through the phosphate groups. Levene thought the chain was short and the bases repeated in a fixed order. In 1937, William Astbury produced the first X-ray diffraction
X-ray diffraction
patterns that showed that DNA
DNA
had a regular structure.[201] In 1927, Nikolai Koltsov proposed that inherited traits would be inherited via a "giant hereditary molecule" made up of "two mirror strands that would replicate in a semi-conservative fashion using each strand as a template".[202][203] In 1928, Frederick Griffith in his experiment discovered that traits of the "smooth" form of Pneumococcus could be transferred to the "rough" form of the same bacteria by mixing killed "smooth" bacteria with the live "rough" form.[204][205] This system provided the first clear suggestion that DNA
DNA
carries genetic information—the Avery–MacLeod–McCarty experiment—when Oswald Avery, along with coworkers Colin MacLeod and Maclyn McCarty, identified DNA
DNA
as the transforming principle in 1943.[206] DNA's role in heredity was confirmed in 1952 when Alfred Hershey and Martha Chase
Martha Chase
in the Hershey–Chase experiment
Hershey–Chase experiment
showed that DNA
DNA
is the genetic material of the T2 phage.[207]

A blue plaque outside The Eagle pub commemorating Crick and Watson

Late in 1951, Francis Crick
Francis Crick
started working with James Watson
James Watson
at the Cavendish Laboratory
Cavendish Laboratory
within the University of Cambridge. In 1953, Watson and Crick suggested what is now accepted as the first correct double-helix model of DNA structure
DNA structure
in the journal Nature.[9] Their double-helix, molecular model of DNA
DNA
was then based on one X-ray diffraction image (labeled as "Photo 51")[208] taken by Rosalind Franklin and Raymond Gosling
Raymond Gosling
in May 1952, and the information that the DNA
DNA
bases are paired. On 28 February 1953 Crick interrupted patrons' lunchtime at The Eagle pub in Cambridge to announce that he and Watson had "discovered the secret of life".[209] Experimental evidence supporting the Watson and Crick model was published in a series of five articles in the same issue of Nature.[210] Of these, Franklin and Gosling's paper was the first publication of their own X-ray diffraction
X-ray diffraction
data and original analysis method that partly supported the Watson and Crick model;[63][211] this issue also contained an article on DNA structure
DNA structure
by Maurice Wilkins and two of his colleagues, whose analysis and in vivo B- DNA
DNA
X-ray patterns also supported the presence in vivo of the double-helical DNA configurations as proposed by Crick and Watson for their double-helix molecular model of DNA
DNA
in the prior two pages of Nature.[64] In 1962, after Franklin's death, Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine.[212] Nobel Prizes are awarded only to living recipients. A debate continues about who should receive credit for the discovery.[213] In an influential presentation in 1957, Crick laid out the central dogma of molecular biology, which foretold the relationship between DNA, RNA, and proteins, and articulated the "adaptor hypothesis".[214] Final confirmation of the replication mechanism that was implied by the double-helical structure followed in 1958 through the Meselson–Stahl experiment.[215] Further work by Crick and coworkers showed that the genetic code was based on non-overlapping triplets of bases, called codons, allowing Har Gobind Khorana, Robert W. Holley, and Marshall Warren Nirenberg
Marshall Warren Nirenberg
to decipher the genetic code.[216] These findings represent the birth of molecular biology.[217]

See also

Autosome Crystallography DNA-encoded chemical library DNA
DNA
microarray DNA
DNA
sequencing Macromolecule Genetic disorder Genetic genealogy Haplotype Comparison of nucleic acid simulation software Meiosis Mitochondrial DNA Nuclear DNA Nucleic acid
Nucleic acid
double helix Nucleic acid
Nucleic acid
notation Nucleic acid
Nucleic acid
sequence Pangenesis Phosphoramidite Ribosomal DNA Southern blot X-ray
X-ray
scattering techniques Xeno nucleic acid RNA Deoxyribozyme

References

^ "deoxyribonucleic acid". Merriam-Webster
Merriam-Webster
Dictionary.  ^ Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P (2014). Molecular Biology
Biology
of the Cell (6th ed.). Garland. p. Chapter 4: DNA, Chromosomes and Genomes. ISBN 9780815344322. Archived from the original on 14 July 2014.  ^ Purcell A. "DNA". Basic Biology. Archived from the original on 5 January 2017.  ^ Russell P (2001). iGenetics. New York: Benjamin Cummings. ISBN 0-8053-4553-1.  ^ Mashaghi A, Katan A (2013). "A physicist's view of DNA". De Physicus. 24e (3): 59–61. arXiv:1311.2545v1 . Bibcode:2013arXiv1311.2545M.  ^ Saenger W (1984). Principles of Nucleic Acid Structure. New York: Springer-Verlag. ISBN 0-387-90762-9.  ^ a b Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Peter W (2002). Molecular Biology
Biology
of the Cell (Fourth ed.). New York and London: Garland Science. ISBN 0-8153-3218-1. OCLC 145080076. Archived from the original on 1 November 2016.  ^ Irobalieva RN, Fogg JM, Catanese DJ, Catanese DJ, Sutthibutpong T, Chen M, Barker AK, Ludtke SJ, Harris SA, Schmid MF, Chiu W, Zechiedrich L (October 2015). "Structural diversity of supercoiled DNA". Nature Communications. 6: 8440. Bibcode:2015NatCo...6E8440I. doi:10.1038/ncomms9440. PMC 4608029 . PMID 26455586.  ^ a b c Watson JD, Crick FH (April 1953). "Molecular structure of nucleic acids; a structure for deoxyribose nucleic acid" (PDF). Nature. 171 (4356): 737–8. Bibcode:1953Natur.171..737W. doi:10.1038/171737a0. PMID 13054692. Archived (PDF) from the original on 4 February 2007.  ^ Mandelkern M, Elias JG, Eden D, Crothers DM (October 1981). "The dimensions of DNA
DNA
in solution". Journal of Molecular Biology. 152 (1): 153–61. doi:10.1016/0022-2836(81)90099-1. PMID 7338906.  ^ Gregory SG, Barlow KF, McLay KE, Kaul R, Swarbreck D, Dunham A, et al. (May 2006). "The DNA sequence
DNA sequence
and biological annotation of human chromosome 1". Nature. 441 (7091): 315–21. Bibcode:2006Natur.441..315G. doi:10.1038/nature04727. PMID 16710414.  ^ Watson JD, Crick FH (April 1953). "Molecular structure of nucleic acids; a structure for deoxyribose nucleic acid" (PDF). Nature. 171 (4356): 737–8. Bibcode:1953Natur.171..737W. doi:10.1038/171737a0. PMID 13054692. Archived (PDF) from the original on 4 February 2007.  ^ a b c Berg J., Tymoczko J. and Stryer L. (2002) Biochemistry. W. H. Freeman and Company ISBN 0-7167-4955-6 ^ Abbreviations and Symbols for Nucleic Acids, Polynucleotides and their Constituents Archived 5 February 2007 at the Wayback Machine. IUPAC-IUB Commission on Biochemical Nomenclature (CBN). Retrieved 3 January 2006. ^ a b Ghosh A, Bansal M (April 2003). "A glossary of DNA
DNA
structures from A to Z". Acta Crystallographica Section D. 59 (Pt 4): 620–6. doi:10.1107/S0907444903003251. PMID 12657780.  ^ Created from PDB 1D65 ^ Yakovchuk P, Protozanova E, Frank-Kamenetskii MD (2006). "Base-stacking and base-pairing contributions into thermal stability of the DNA
DNA
double helix". Nucleic Acids Research. 34 (2): 564–74. doi:10.1093/nar/gkj454. PMC 1360284 . PMID 16449200.  ^ Tropp BE (2012). Molecular Biology
Biology
(4th ed.). Sudbury, Mass.: Jones and Barlett Learning. ISBN 978-0-7637-8663-2.  ^ Carr S (1953). "Watson-Crick Structure of DNA". Memorial University of Newfoundland. Archived from the original on 19 July 2016. Retrieved 13 July 2016.  ^ Verma S, Eckstein F (1998). "Modified oligonucleotides: synthesis and strategy for users". Annual Review of Biochemistry. 67: 99–134. doi:10.1146/annurev.biochem.67.1.99. PMID 9759484.  ^ Kiljunen S, Hakala K, Pinta E, Huttunen S, Pluta P, Gador A, Lönnberg H, Skurnik M (December 2005). "Yersiniophage phiR1-37 is a tailed bacteriophage having a 270 kb DNA
DNA
genome with thymidine replaced by deoxyuridine". Microbiology. 151 (Pt 12): 4093–102. doi:10.1099/mic.0.28265-0. PMID 16339954.  ^ Uchiyama J, Takemura-Uchiyama I, Sakaguchi Y, Gamoh K, Kato S, Daibata M, Ujihara T, Misawa N, Matsuzaki S (September 2014). "Intragenus generalized transduction in Staphylococcus spp. by a novel giant phage". The ISME Journal. 8 (9): 1949–52. doi:10.1038/ismej.2014.29. PMC 4139722 . PMID 24599069.  ^ Casella E, Markewych O, Dosmar M, Heman W (1978) Production and expression of dTMP-enriched DNA
DNA
of bacteriophage SP15. J Virology 28 (3) 753–766 ^ Simpson L (March 1998). "A base called J". Proceedings of the National Academy of Sciences of the United States of America. 95 (5): 2037–8. Bibcode:1998PNAS...95.2037S. doi:10.1073/pnas.95.5.2037. PMC 33841 . PMID 9482833.  ^ Borst P, Sabatini R (2008). "Base J: discovery, biosynthesis, and possible functions". Annual Review of Microbiology. 62: 235–51. doi:10.1146/annurev.micro.62.081307.162750. PMID 18729733.  ^ Cross M, Kieft R, Sabatini R, Wilm M, de Kort M, van der Marel GA, van Boom JH, van Leeuwen F, Borst P (November 1999). "The modified base J is the target for a novel DNA-binding protein
DNA-binding protein
in kinetoplastid protozoans". The EMBO Journal. 18 (22): 6573–81. doi:10.1093/emboj/18.22.6573. PMC 1171720 . PMID 10562569.  ^ DiPaolo C, Kieft R, Cross M, Sabatini R (February 2005). "Regulation of trypanosome DNA
DNA
glycosylation by a SWI2/SNF2-like protein". Molecular Cell. 17 (3): 441–51. doi:10.1016/j.molcel.2004.12.022. PMID 15694344.  ^ Vainio S, Genest PA, ter Riet B, van Luenen H, Borst P (April 2009). "Evidence that J-binding protein 2 is a thymidine hydroxylase catalyzing the first step in the biosynthesis of DNA
DNA
base J". Molecular and Biochemical Parasitology. 164 (2): 157–61. doi:10.1016/j.molbiopara.2008.12.001. PMID 19114062.  ^ Iyer LM, Tahiliani M, Rao A, Aravind L (June 2009). "Prediction of novel families of enzymes involved in oxidative and other complex modifications of bases in nucleic acids". Cell Cycle. 8 (11): 1698–710. doi:10.4161/cc.8.11.8580. PMC 2995806 . PMID 19411852.  ^ van Luenen HG, Farris C, Jan S, Genest PA, Tripathi P, Velds A, Kerkhoven RM, Nieuwland M, Haydock A, Ramasamy G, Vainio S, Heidebrecht T, Perrakis A, Pagie L, van Steensel B, Myler PJ, Borst P (August 2012). "Glucosylated hydroxymethyluracil, DNA
DNA
base J, prevents transcriptional readthrough in Leishmania". Cell. 150 (5): 909–21. doi:10.1016/j.cell.2012.07.030. PMC 3684241 . PMID 22939620.  ^ Hazelbaker DZ, Buratowski S (November 2012). "Transcription: base J blocks the way". Current Biology. 22 (22): R960–2. doi:10.1016/j.cub.2012.10.010. PMC 3648658 . PMID 23174300.  ^ Khudyakov IY, Kirnos MD, Alexandrushkina NI, Vanyushin BF (1978). "Cyanophage S-2L contains DNA
DNA
with 2,6-diaminopurine substituted for adenine". Virology. 88 (1): 8–18. PMID 676082.  ^ Thiaville JJ, Kellner SM, Yuan Y, Hutinet G, Thiaville PC, Jumpathong W, Mohapatra S, Brochier-Armanet C, Letarov AV, Hillebrand R, Malik CK, Rizzo CJ, Dedon PC, de Crécy-Lagard V (2016). "Novel genomic island modifies DNA
DNA
with 7-deazaguanine derivatives". Proceedings of the National Academy of Sciences of the United States of America. 113 (11): E1452–9. doi:10.1073/pnas.1518570113. PMC 4801273 . PMID 26929322.  ^ Johnson TB, Coghill RD (1925). "Pyrimidines. CIII. The discovery of 5-methylcytosine in tuberculinic acid, the nucleic acid of the tubercle bacillus". Journal of the American Chemical Society. 47: 2838–44.  ^ Wyatt GR, Cohen SS (1953). "The bases of the nucleic acids of some bacterial and animal viruses: the occurrence of 5-hydroxymethylcytosine". The Biochemical Journal. 55 (5): 774–82. PMC 1269533 . PMID 13115372.  ^ Kuo TT, Huang TC, Teng MH (1968). "5- Methylcytosine
Methylcytosine
replacing cytosine in the deoxyribonucleic acid of a bacteriophage for Xanthomonas oryzae". Journal of Molecular Biology. 34 (2): 373–5. PMID 5760463.  ^ Vogelsang-Wenke H, Oesterhelt D (March 1988). "Isolation of a halobacterial phage with a fully cytosine-methylated genome". MGG Molecular & General Genetics. 211 (3): 407–414. doi:10.1007/BF00425693.  ^ Dunn DB, Smith JD (1955). "Occurrence of a new base in the deoxyribonucleic acid of a strain of Bacterium
Bacterium
coli". Nature. 175 (4451): 336–7. PMID 13235889.  ^ Allet B, Bukhari AI (1975). "Analysis of bacteriophage mu and lambda-mu hybrid DNAs by specific endonucleases". Journal of Molecular Biology. 92 (4): 529–40. PMID 1097703.  ^ Nikolskaya II, Lopatina NG, Debov SS (1976). "Methylated guanine derivative as a minor base in the DNA
DNA
of phage DDVI Shigella disenteriae". Biochimica et Biophysica Acta. 435 (2): 206–10. PMID 779843.  ^ Janulaitis A, Klimasauskas S, Petrusyte M, Butkus V (1983). " Cytosine
Cytosine
modification in DNA
DNA
by BcnI methylase yields N4-methylcytosine". FEBS Letters. 161 (1): 131–4. PMID 6884523.  ^ Swinton D, Hattman S, Benzinger R, Buchanan-Wollaston V, Beringer J (1985). "Replacement of the deoxycytidine residues in Rhizobium bacteriophage RL38JI DNA". FEBS Letters. 184 (2): 294–8. PMID 2987032.  ^ Maltman KL, Neuhard J, Warren RA (1981). "5-[(Hydroxymethyl)-O-pyrophosphoryl]uracil, an intermediate in the biosynthesis of alpha-putrescinylthymine in deoxyribonucleic acid of bacteriophage phi W-14". Biochemistry. 20 (12): 3586–91. PMID 7260058.  ^ Carell T, Kurz MQ, Müller M, Rossa M, Spada F (2017). "Non-canonical bases in the genome: The regulatory information layer in DNA". Angewandte Chemie (International Ed. in English). doi:10.1002/anie.201708228. PMID 28941008.  ^ Wing R, Drew H, Takano T, Broka C, Tanaka S, Itakura K, Dickerson RE (October 1980). "Crystal structure analysis of a complete turn of B-DNA". Nature. 287 (5784): 755–8. Bibcode:1980Natur.287..755W. doi:10.1038/287755a0. PMID 7432492.  ^ a b Pabo CO, Sauer RT (1984). "Protein- DNA
DNA
recognition". Annual Review of Biochemistry. 53: 293–321. doi:10.1146/annurev.bi.53.070184.001453. PMID 6236744.  ^ Nikolova EN, Zhou H, Gottardo FL, Alvey HS, Kimsey IJ, Al-Hashimi HM (2013). "A historical account of Hoogsteen base-pairs in duplex DNA". Biopolymers. 99 (12): 955–68. doi:10.1002/bip.22334. PMC 3844552 . PMID 23818176.  ^ Clausen-Schaumann H, Rief M, Tolksdorf C, Gaub HE (April 2000). "Mechanical stability of single DNA
DNA
molecules". Biophysical Journal. 78 (4): 1997–2007. Bibcode:2000BpJ....78.1997C. doi:10.1016/S0006-3495(00)76747-6. PMC 1300792 . PMID 10733978.  ^ Chalikian TV, Völker J, Plum GE, Breslauer KJ (July 1999). "A more unified picture for the thermodynamics of nucleic acid duplex melting: a characterization by calorimetric and volumetric techniques". Proceedings of the National Academy of Sciences of the United States of America. 96 (14): 7853–8. Bibcode:1999PNAS...96.7853C. doi:10.1073/pnas.96.14.7853. PMC 22151 . PMID 10393911.  ^ deHaseth PL, Helmann JD (June 1995). "Open complex formation by Escherichia
Escherichia
coli RNA
RNA
polymerase: the mechanism of polymerase-induced strand separation of double helical DNA". Molecular Microbiology. 16 (5): 817–24. doi:10.1111/j.1365-2958.1995.tb02309.x. PMID 7476180.  ^ Isaksson J, Acharya S, Barman J, Cheruku P, Chattopadhyaya J (December 2004). "Single-stranded adenine-rich DNA
DNA
and RNA
RNA
retain structural characteristics of their respective double-stranded conformations and show directional differences in stacking pattern" (PDF). Biochemistry. 43 (51): 15996–6010. doi:10.1021/bi048221v. PMID 15609994. Archived (PDF) from the original on 10 June 2007.  ^ Designation of the two strands of DNA
DNA
Archived 24 April 2008 at the Wayback Machine. JCBN/NC-IUB Newsletter 1989. Retrieved 7 May 2008 ^ Hüttenhofer A, Schattner P, Polacek N (May 2005). "Non-coding RNAs: hope or hype?". Trends in Genetics. 21 (5): 289–97. doi:10.1016/j.tig.2005.03.007. PMID 15851066.  ^ Munroe SH (November 2004). "Diversity of antisense regulation in eukaryotes: multiple mechanisms, emerging patterns". Journal of Cellular Biochemistry. 93 (4): 664–71. doi:10.1002/jcb.20252. PMID 15389973.  ^ Makalowska I, Lin CF, Makalowski W (February 2005). "Overlapping genes in vertebrate genomes". Computational Biology
Biology
and Chemistry. 29 (1): 1–12. doi:10.1016/j.compbiolchem.2004.12.006. PMID 15680581.  ^ Johnson ZI, Chisholm SW (November 2004). "Properties of overlapping genes are conserved across microbial genomes". Genome
Genome
Research. 14 (11): 2268–72. doi:10.1101/gr.2433104. PMC 525685 . PMID 15520290.  ^ Lamb RA, Horvath CM (August 1991). "Diversity of coding strategies in influenza viruses". Trends in Genetics. 7 (8): 261–6. doi:10.1016/0168-9525(91)90326-L. PMID 1771674.  ^ Benham CJ, Mielke SP (2005). " DNA
DNA
mechanics". Annual Review of Biomedical Engineering. 7: 21–53. doi:10.1146/annurev.bioeng.6.062403.132016. PMID 16004565.  ^ a b Champoux JJ (2001). " DNA
DNA
topoisomerases: structure, function, and mechanism". Annual Review of Biochemistry. 70: 369–413. doi:10.1146/annurev.biochem.70.1.369. PMID 11395412.  ^ a b Wang JC (June 2002). "Cellular roles of DNA
DNA
topoisomerases: a molecular perspective". Nature Reviews. Molecular Cell Biology. 3 (6): 430–40. doi:10.1038/nrm831. PMID 12042765.  ^ Basu HS, Feuerstein BG, Zarling DA, Shafer RH, Marton LJ (October 1988). "Recognition of Z- RNA
RNA
and Z-DNA
Z-DNA
determinants by polyamines in solution: experimental and theoretical studies". Journal of Biomolecular Structure & Dynamics. 6 (2): 299–309. doi:10.1080/07391102.1988.10507714. PMID 2482766.  ^ Franklin RE, Gosling RG (6 March 1953). "The Structure of Sodium Thymonucleate Fibres I. The Influence of Water Content" (PDF). Acta Crystallogr. 6 (8–9): 673–7. doi:10.1107/S0365110X53001939. Archived (PDF) from the original on 9 January 2016.  Franklin RE, Gosling RG (1953). "The structure of sodium thymonucleate fibres. II. The cylindrically symmetrical Patterson function". Acta Crystallogr. 6 (8–9): 678–85. doi:10.1107/S0365110X53001940.  ^ a b Franklin RE, Gosling RG (April 1953). "Molecular configuration in sodium thymonucleate" (PDF). Nature. 171 (4356): 740–1. Bibcode:1953Natur.171..740F. doi:10.1038/171740a0. PMID 13054694. Archived (PDF) from the original on 3 January 2011.  ^ a b Wilkins MH, Stokes AR, Wilson HR (April 1953). "Molecular structure of deoxypentose nucleic acids" (PDF). Nature. 171 (4356): 738–40. Bibcode:1953Natur.171..738W. doi:10.1038/171738a0. PMID 13054693. Archived (PDF) from the original on 13 May 2011.  ^ Leslie AG, Arnott S, Chandrasekaran R, Ratliff RL (October 1980). "Polymorphism of DNA
DNA
double helices". Journal of Molecular Biology. 143 (1): 49–72. doi:10.1016/0022-2836(80)90124-2. PMID 7441761.  ^ Baianu IC (1980). "Structural Order and Partial Disorder in Biological systems". Bull. Math. Biol. 42 (4): 137–141. doi:10.1007/BF02462372.  "Archived copy". Archived from the original on 25 July 2009. Retrieved 6 May 2009.  ^ Hosemann R, Bagchi RN (1962). Direct analysis of diffraction by matter. Amsterdam – New York: North-Holland Publishers.  ^ Baianu IC (1978). " X-ray
X-ray
scattering by partially disordered membrane systems". Acta Crystallogr A. 34 (5): 751–753. Bibcode:1978AcCrA..34..751B. doi:10.1107/S0567739478001540.  ^ Wahl MC, Sundaralingam M (1997). "Crystal structures of A-DNA duplexes". Biopolymers. 44 (1): 45–63. doi:10.1002/(SICI)1097-0282(1997)44:1<45::AID-BIP4>3.0.CO;2-#. PMID 9097733.  ^ Lu XJ, Shakked Z, Olson WK (July 2000). "A-form conformational motifs in ligand-bound DNA
DNA
structures". Journal of Molecular Biology. 300 (4): 819–40. doi:10.1006/jmbi.2000.3690. PMID 10891271.  ^ Rothenburg S, Koch-Nolte F, Haag F (December 2001). " DNA
DNA
methylation and Z-DNA
Z-DNA
formation as mediators of quantitative differences in the expression of alleles". Immunological Reviews. 184: 286–98. doi:10.1034/j.1600-065x.2001.1840125.x. PMID 12086319.  ^ Oh DB, Kim YG, Rich A (December 2002). "Z-DNA-binding proteins can act as potent effectors of gene expression in vivo". Proceedings of the National Academy of Sciences of the United States of America. 99 (26): 16666–71. Bibcode:2002PNAS...9916666O. doi:10.1073/pnas.262672699. PMC 139201 . PMID 12486233.  ^ a b Palmer J (2 December 2010). "Arsenic-loving bacteria may help in hunt for alien life". BBC News. Archived from the original on 3 December 2010. Retrieved 2 December 2010.  ^ a b Bortman, Henry (2 December 2010). "Arsenic-Eating Bacteria
Bacteria
Opens New Possibilities for Alien Life". Space.com. Archived from the original on 4 December 2010. Retrieved 2 December 2010.  ^ Katsnelson A (2 December 2010). "Arsenic-eating microbe may redefine chemistry of life". Nature News. doi:10.1038/news.2010.645. Archived from the original on 24 February 2012.  ^ Cressey D (3 October 2012). "'Arsenic-life' Bacterium
Bacterium
Prefers Phosphorus after all". Nature News. doi:10.1038/nature.2012.11520.  ^ a b Greider CW, Blackburn EH (December 1985). "Identification of a specific telomere terminal transferase activity in Tetrahymena extracts". Cell. 43 (2 Pt 1): 405–13. doi:10.1016/0092-8674(85)90170-9. PMID 3907856.  ^ a b c Nugent CI, Lundblad V (April 1998). "The telomerase reverse transcriptase: components and regulation". Genes & Development. 12 (8): 1073–85. doi:10.1101/gad.12.8.1073. PMID 9553037.  ^ Wright WE, Tesmer VM, Huffman KE, Levene SD, Shay JW (November 1997). "Normal human chromosomes have long G-rich telomeric overhangs at one end". Genes & Development. 11 (21): 2801–9. doi:10.1101/gad.11.21.2801. PMC 316649 . PMID 9353250.  ^ Created from Archived 17 October 2016 at the Wayback Machine. ^ a b Burge S, Parkinson GN, Hazel P, Todd AK, Neidle S (2006). "Quadruplex DNA: sequence, topology and structure". Nucleic Acids Research. 34 (19): 5402–15. doi:10.1093/nar/gkl655. PMC 1636468 . PMID 17012276.  ^ Parkinson GN, Lee MP, Neidle S (June 2002). "Crystal structure of parallel quadruplexes from human telomeric DNA". Nature. 417 (6891): 876–80. Bibcode:2002Natur.417..876P. doi:10.1038/nature755. PMID 12050675.  ^ Griffith JD, Comeau L, Rosenfield S, Stansel RM, Bianchi A, Moss H, de Lange T (May 1999). "Mammalian telomeres end in a large duplex loop". Cell. 97 (4): 503–14. doi:10.1016/S0092-8674(00)80760-6. PMID 10338214.  ^ Seeman NC (November 2005). " DNA
DNA
enables nanoscale control of the structure of matter". Quarterly Reviews of Biophysics. 38 (4): 363–71. doi:10.1017/S0033583505004087. PMC 3478329 . PMID 16515737.  ^ Hu Q, Rosenfeld MG (2012). "Epigenetic regulation of human embryonic stem cells". Frontiers in Genetics. 3: 238. doi:10.3389/fgene.2012.00238. PMC 3488762 . PMID 23133442.  ^ Klose RJ, Bird AP (February 2006). " Genomic DNA methylation: the mark and its mediators". Trends in Biochemical Sciences. 31 (2): 89–97. doi:10.1016/j.tibs.2005.12.008. PMID 16403636.  ^ Bird A (January 2002). " DNA methylation
DNA methylation
patterns and epigenetic memory". Genes & Development. 16 (1): 6–21. doi:10.1101/gad.947102. PMID 11782440.  ^ Walsh CP, Xu GL (2006). " Cytosine
Cytosine
methylation and DNA
DNA
repair". Current Topics in Microbiology and Immunology. Current Topics in Microbiology and Immunology. 301: 283–315. doi:10.1007/3-540-31390-7_11. ISBN 3-540-29114-8. PMID 16570853.  ^ Kriaucionis S, Heintz N (May 2009). "The nuclear DNA
DNA
base 5-hydroxymethylcytosine
5-hydroxymethylcytosine
is present in Purkinje neurons and the brain". Science. 324 (5929): 929–30. Bibcode:2009Sci...324..929K. doi:10.1126/science.1169786. PMC 3263819 . PMID 19372393.  ^ Ratel D, Ravanat JL, Berger F, Wion D (March 2006). "N6-methyladenine: the other methylated base of DNA". BioEssays. 28 (3): 309–15. doi:10.1002/bies.20342. PMC 2754416 . PMID 16479578.  ^ Gommers-Ampt JH, Van Leeuwen F, de Beer AL, Vliegenthart JF, Dizdaroglu M, Kowalak JA, Crain PF, Borst P (December 1993). "beta-D-glucosyl-hydroxymethyluracil: a novel modified base present in the DNA
DNA
of the parasitic protozoan T. brucei". Cell. 75 (6): 1129–36. doi:10.1016/0092-8674(93)90322-H. PMID 8261512.  ^ Created from PDB 1JDG ^ Douki T, Reynaud-Angelin A, Cadet J, Sage E (August 2003). "Bipyrimidine photoproducts rather than oxidative lesions are the main type of DNA
DNA
damage involved in the genotoxic effect of solar UVA radiation". Biochemistry. 42 (30): 9221–6. doi:10.1021/bi034593c. PMID 12885257.  ^ Cadet J, Delatour T, Douki T, Gasparutto D, Pouget JP, Ravanat JL, Sauvaigo S (March 1999). " Hydroxyl
Hydroxyl
radicals and DNA
DNA
base damage". Mutation
Mutation
Research. 424 (1–2): 9–21. doi:10.1016/S0027-5107(99)00004-4. PMID 10064846.  ^ Beckman KB, Ames BN (August 1997). "Oxidative decay of DNA". The Journal of Biological Chemistry. 272 (32): 19633–6. doi:10.1074/jbc.272.32.19633. PMID 9289489.  ^ Valerie K, Povirk LF (September 2003). "Regulation and mechanisms of mammalian double-strand break repair". Oncogene. 22 (37): 5792–812. doi:10.1038/sj.onc.1206679. PMID 12947387.  ^ Johnson G (28 December 2010). "Unearthing Prehistoric Tumors, and Debate". The New York Times. Archived from the original on 24 June 2017. If we lived long enough, sooner or later we all would get cancer.  ^ Alberts B, Johnson A, Lewis J, et al. (2002). "The Preventable Causes of Cancer". Molecular biology
Molecular biology
of the cell (4th ed.). New York: Garland Science. ISBN 0-8153-4072-9. Archived from the original on 2 January 2016. A certain irreducible background incidence of cancer is to be expected regardless of circumstances: mutations can never be absolutely avoided, because they are an inescapable consequence of fundamental limitations on the accuracy of DNA replication, as discussed in Chapter 5. If a human could live long enough, it is inevitable that at least one of his or her cells would eventually accumulate a set of mutations sufficient for cancer to develop.  ^ Bernstein H, Payne CM, Bernstein C, Garewal H, Dvorak K (2008). " Cancer
Cancer
and aging as consequences of un-repaired DNA
DNA
damage". In Kimura H, Suzuki A. New Research on DNA
DNA
Damage. New York: Nova Science Publishers. pp. 1–47. ISBN 978-1-60456-581-2. Archived from the original on 25 October 2014.  ^ Hoeijmakers JH (October 2009). " DNA
DNA
damage, aging, and cancer". The New England Journal of Medicine. 361 (15): 1475–85. doi:10.1056/NEJMra0804615. PMID 19812404.  ^ Freitas AA, de Magalhães JP (2011). "A review and appraisal of the DNA
DNA
damage theory of ageing". Mutation
Mutation
Research. 728 (1–2): 12–22. doi:10.1016/j.mrrev.2011.05.001. PMID 21600302.  ^ Ferguson LR, Denny WA (September 1991). "The genetic toxicology of acridines". Mutation
Mutation
Research. 258 (2): 123–60. doi:10.1016/0165-1110(91)90006-H. PMID 1881402.  ^ Stephens TD, Bunde CJ, Fillmore BJ (June 2000). "Mechanism of action in thalidomide teratogenesis". Biochemical Pharmacology. 59 (12): 1489–99. doi:10.1016/S0006-2952(99)00388-3. PMID 10799645.  ^ Jeffrey AM (1985). " DNA
DNA
modification by chemical carcinogens". Pharmacology & Therapeutics. 28 (2): 237–72. doi:10.1016/0163-7258(85)90013-0. PMID 3936066.  ^ Braña MF, Cacho M, Gradillas A, de Pascual-Teresa B, Ramos A (November 2001). "Intercalators as anticancer drugs". Current Pharmaceutical Design. 7 (17): 1745–80. doi:10.2174/1381612013397113. PMID 11562309.  ^ Venter JC, Adams MD, Myers EW, Li PW, Mural RJ, Sutton GG, et al. (February 2001). "The sequence of the human genome". Science. 291 (5507): 1304–51. Bibcode:2001Sci...291.1304V. doi:10.1126/science.1058040. PMID 11181995.  ^ Thanbichler M, Wang SC, Shapiro L (October 2005). "The bacterial nucleoid: a highly organized and dynamic structure". Journal of Cellular Biochemistry. 96 (3): 506–21. doi:10.1002/jcb.20519. PMID 15988757.  ^ Wolfsberg TG, McEntyre J, Schuler GD (February 2001). "Guide to the draft human genome". Nature. 409 (6822): 824–6. Bibcode:2001Natur.409..824W. doi:10.1038/35057000. PMID 11236998.  ^ Gregory TR (January 2005). "The C-value enigma in plants and animals: a review of parallels and an appeal for partnership". Annals of Botany. 95 (1): 133–46. doi:10.1093/aob/mci009. PMID 15596463.  ^ Birney E, Stamatoyannopoulos JA, Dutta A, Guigó R, Gingeras TR, Margulies EH, et al. (June 2007). "Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project". Nature. 447 (7146): 799–816. Bibcode:2007Natur.447..799B. doi:10.1038/nature05874. PMC 2212820 . PMID 17571346.  ^ Created from PDB 1MSW Archived 6 January 2008 at the Wayback Machine. ^ Pidoux AL, Allshire RC (March 2005). "The role of heterochromatin in centromere function". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 360 (1455): 569–79. doi:10.1098/rstb.2004.1611. PMC 1569473 . PMID 15905142.  ^ Harrison PM, Hegyi H, Balasubramanian S, Luscombe NM, Bertone P, Echols N, Johnson T, Gerstein M (February 2002). "Molecular fossils in the human genome: identification and analysis of the pseudogenes in chromosomes 21 and 22". Genome
Genome
Research. 12 (2): 272–80. doi:10.1101/gr.207102. PMC 155275 . PMID 11827946.  ^ Harrison PM, Gerstein M (May 2002). "Studying genomes through the aeons: protein families, pseudogenes and proteome evolution". Journal of Molecular Biology. 318 (5): 1155–74. doi:10.1016/S0022-2836(02)00109-2. PMID 12083509.  ^ Albà M (2001). "Replicative DNA
DNA
polymerases". Genome
Genome
Biology. 2 (1): REVIEWS3002. doi:10.1186/gb-2001-2-1-reviews3002. PMC 150442 . PMID 11178285.  ^ Tani K, Nasu M (2010). "Roles of Extracellular DNA
DNA
in Bacterial Ecosystems". In Kikuchi Y, Rykova EY. Extracellular Nucleic Acids. Springer. pp. 25–38. ISBN 978-3-642-12616-1.  ^ Vlassov VV, Laktionov PP, Rykova EY (July 2007). "Extracellular nucleic acids". BioEssays. 29 (7): 654–67. doi:10.1002/bies.20604. PMID 17563084.  ^ Finkel SE, Kolter R (November 2001). " DNA
DNA
as a nutrient: novel role for bacterial competence gene homologs". Journal of Bacteriology. 183 (21): 6288–93. doi:10.1128/JB.183.21.6288-6293.2001. PMC 100116 . PMID 11591672.  ^ Mulcahy H, Charron-Mazenod L, Lewenza S (November 2008). "Extracellular DNA
DNA
chelates cations and induces antibiotic resistance in Pseudomonas aeruginosa biofilms". PLoS Pathogens. 4 (11): e1000213. doi:10.1371/journal.ppat.1000213. PMC 2581603 . PMID 19023416.  ^ Berne C, Kysela DT, Brun YV (August 2010). "A bacterial extracellular DNA
DNA
inhibits settling of motile progeny cells within a biofilm". Molecular Microbiology. 77 (4): 815–29. doi:10.1111/j.1365-2958.2010.07267.x. PMC 2962764 . PMID 20598083.  ^ Whitchurch CB, Tolker-Nielsen T, Ragas PC, Mattick JS (February 2002). "Extracellular DNA
DNA
required for bacterial biofilm formation". Science. 295 (5559): 1487. doi:10.1126/science.295.5559.1487. PMID 11859186.  ^ Hu W, Li L, Sharma S, Wang J, McHardy I, Lux R, Yang Z, He X, Gimzewski JK, Li Y, Shi W (2012). " DNA
DNA
builds and strengthens the extracellular matrix in Myxococcus xanthus biofilms by interacting with exopolysaccharides". PLoS One. 7 (12): e51905. Bibcode:2012PLoSO...751905H. doi:10.1371/journal.pone.0051905. PMC 3530553 . PMID 23300576.  ^ Hui L, Bianchi DW (February 2013). "Recent advances in the prenatal interrogation of the human fetal genome". Trends in Genetics. 29 (2): 84–91. doi:10.1016/j.tig.2012.10.013. PMC 4378900 . PMID 23158400.  ^ Sandman K, Pereira SL, Reeve JN (December 1998). "Diversity of prokaryotic chromosomal proteins and the origin of the nucleosome". Cellular and Molecular Life
Life
Sciences. 54 (12): 1350–64. doi:10.1007/s000180050259. PMID 9893710.  ^ Dame RT (May 2005). "The role of nucleoid-associated proteins in the organization and compaction of bacterial chromatin". Molecular Microbiology. 56 (4): 858–70. doi:10.1111/j.1365-2958.2005.04598.x. PMID 15853876.  ^ Luger K, Mäder AW, Richmond RK, Sargent DF, Richmond TJ (September 1997). "Crystal structure of the nucleosome core particle at 2.8 A resolution". Nature. 389 (6648): 251–60. Bibcode:1997Natur.389..251L. doi:10.1038/38444. PMID 9305837.  ^ Jenuwein T, Allis CD (August 2001). "Translating the histone code" (PDF). Science. 293 (5532): 1074–80. doi:10.1126/science.1063127. PMID 11498575. Archived (PDF) from the original on 8 August 2017.  ^ Ito T (2003). " Nucleosome
Nucleosome
assembly and remodeling". Current Topics in Microbiology and Immunology. Current Topics in Microbiology and Immunology. 274: 1–22. doi:10.1007/978-3-642-55747-7_1. ISBN 978-3-540-44208-0. PMID 12596902.  ^ Thomas JO (August 2001). "HMG1 and 2: architectural DNA-binding proteins". Biochemical Society Transactions. 29 (Pt 4): 395–401. doi:10.1042/BST0290395. PMID 11497996.  ^ Grosschedl R, Giese K, Pagel J (March 1994). "HMG domain proteins: architectural elements in the assembly of nucleoprotein structures". Trends in Genetics. 10 (3): 94–100. doi:10.1016/0168-9525(94)90232-1. PMID 8178371.  ^ Iftode C, Daniely Y, Borowiec JA (1999). "Replication protein A (RPA): the eukaryotic SSB". Critical Reviews in Biochemistry
Biochemistry
and Molecular Biology. 34 (3): 141–80. doi:10.1080/10409239991209255. PMID 10473346.  ^ Created from PDB 1LMB Archived 6 January 2008 at the Wayback Machine. ^ Myers LC, Kornberg RD (2000). "Mediator of transcriptional regulation". Annual Review of Biochemistry. 69: 729–49. doi:10.1146/annurev.biochem.69.1.729. PMID 10966474.  ^ Spiegelman BM, Heinrich R (October 2004). "Biological control through regulated transcriptional coactivators". Cell. 119 (2): 157–67. doi:10.1016/j.cell.2004.09.037. PMID 15479634.  ^ Li Z, Van Calcar S, Qu C, Cavenee WK, Zhang MQ, Ren B (July 2003). "A global transcriptional regulatory role for c-Myc in Burkitt's lymphoma cells". Proceedings of the National Academy of Sciences of the United States of America. 100 (14): 8164–9. Bibcode:2003PNAS..100.8164L. doi:10.1073/pnas.1332764100. PMC 166200 . PMID 12808131.  ^ Created from PDB 1RVA Archived 6 January 2008 at the Wayback Machine. ^ Bickle TA, Krüger DH (June 1993). " Biology
Biology
of DNA
DNA
restriction". Microbiological Reviews. 57 (2): 434–50. PMC 372918 . PMID 8336674.  ^ a b Doherty AJ, Suh SW (November 2000). "Structural and mechanistic conservation in DNA
DNA
ligases". Nucleic Acids Research. 28 (21): 4051–8. doi:10.1093/nar/28.21.4051. PMC 113121 . PMID 11058099.  ^ Schoeffler AJ, Berger JM (December 2005). "Recent advances in understanding structure-function relationships in the type II topoisomerase mechanism". Biochemical Society Transactions. 33 (Pt 6): 1465–70. doi:10.1042/BST20051465. PMID 16246147.  ^ Tuteja N, Tuteja R (May 2004). "Unraveling DNA
DNA
helicases. Motif, structure, mechanism and function". European Journal of Biochemistry. 271 (10): 1849–63. doi:10.1111/j.1432-1033.2004.04094.x. PMID 15128295.  ^ Joyce CM, Steitz TA (November 1995). " Polymerase
Polymerase
structures and function: variations on a theme?". Journal of Bacteriology. 177 (22): 6321–9. doi:10.1128/jb.177.22.6321-6329.1995. PMC 177480 . PMID 7592405.  ^ Hubscher U, Maga G, Spadari S (2002). "Eukaryotic DNA
DNA
polymerases". Annual Review of Biochemistry. 71: 133–63. doi:10.1146/annurev.biochem.71.090501.150041. PMID 12045093.  ^ Johnson A, O'Donnell M (2005). "Cellular DNA
DNA
replicases: components and dynamics at the replication fork". Annual Review of Biochemistry. 74: 283–315. doi:10.1146/annurev.biochem.73.011303.073859. PMID 15952889.  ^ a b Tarrago-Litvak L, Andréola ML, Nevinsky GA, Sarih-Cottin L, Litvak S (May 1994). "The reverse transcriptase of HIV-1: from enzymology to therapeutic intervention". FASEB Journal. 8 (8): 497–503. PMID 7514143.  ^ Martinez E (December 2002). "Multi-protein complexes in eukaryotic gene transcription". Plant
Plant
Molecular Biology. 50 (6): 925–47. doi:10.1023/A:1021258713850. PMID 12516863.  ^ Created from PDB 1M6G Archived 10 January 2010 at the Wayback Machine. ^ Cremer T, Cremer C (April 2001). " Chromosome
Chromosome
territories, nuclear architecture and gene regulation in mammalian cells". Nature Reviews. Genetics. 2 (4): 292–301. doi:10.1038/35066075. PMID 11283701.  ^ Pál C, Papp B, Lercher MJ (May 2006). "An integrated view of protein evolution". Nature Reviews. Genetics. 7 (5): 337–48. doi:10.1038/nrg1838. PMID 16619049.  ^ O'Driscoll M, Jeggo PA (January 2006). "The role of double-strand break repair - insights from human genetics". Nature Reviews. Genetics. 7 (1): 45–54. doi:10.1038/nrg1746. PMID 16369571.  ^ Vispé S, Defais M (October 1997). "Mammalian Rad51 protein: a RecA homologue with pleiotropic functions". Biochimie. 79 (9–10): 587–92. doi:10.1016/S0300-9084(97)82007-X. PMID 9466696.  ^ Neale MJ, Keeney S (July 2006). "Clarifying the mechanics of DNA strand exchange in meiotic recombination". Nature. 442 (7099): 153–8. Bibcode:2006Natur.442..153N. doi:10.1038/nature04885. PMC 5607947 . PMID 16838012.  ^ Dickman MJ, Ingleston SM, Sedelnikova SE, Rafferty JB, Lloyd RG, Grasby JA, Hornby DP (November 2002). "The RuvABC resolvasome". European Journal of Biochemistry. 269 (22): 5492–501. doi:10.1046/j.1432-1033.2002.03250.x. PMID 12423347.  ^ Joyce GF (July 2002). "The antiquity of RNA-based evolution". Nature. 418 (6894): 214–21. Bibcode:2002Natur.418..214J. doi:10.1038/418214a. PMID 12110897.  ^ Orgel LE (2004). "Prebiotic chemistry and the origin of the RNA world". Critical Reviews in Biochemistry
Biochemistry
and Molecular Biology. 39 (2): 99–123. CiteSeerX 10.1.1.537.7679 . doi:10.1080/10409230490460765. PMID 15217990.  ^ Davenport RJ (May 2001). "Ribozymes. Making copies in the RNA world". Science. 292 (5520): 1278. doi:10.1126/science.292.5520.1278a. PMID 11360970.  ^ Szathmáry E (April 1992). "What is the optimum size for the genetic alphabet?". Proceedings of the National Academy of Sciences of the United States of America. 89 (7): 2614–8. Bibcode:1992PNAS...89.2614S. doi:10.1073/pnas.89.7.2614. PMC 48712 . PMID 1372984.  ^ Lindahl T (April 1993). "Instability and decay of the primary structure of DNA". Nature. 362 (6422): 709–15. Bibcode:1993Natur.362..709L. doi:10.1038/362709a0. PMID 8469282.  ^ Vreeland RH, Rosenzweig WD, Powers DW (October 2000). "Isolation of a 250 million-year-old halotolerant bacterium from a primary salt crystal". Nature. 407 (6806): 897–900. Bibcode:2000Natur.407..897V. doi:10.1038/35038060. PMID 11057666.  ^ Hebsgaard MB, Phillips MJ, Willerslev E (May 2005). "Geologically ancient DNA: fact or artefact?". Trends in Microbiology. 13 (5): 212–20. doi:10.1016/j.tim.2005.03.010. PMID 15866038.  ^ Nickle DC, Learn GH, Rain MW, Mullins JI, Mittler JE (January 2002). "Curiously modern DNA
DNA
for a "250 million-year-old" bacterium". Journal of Molecular Evolution. 54 (1): 134–7. Bibcode:2002JMolE..54..134N. doi:10.1007/s00239-001-0025-x. PMID 11734907.  ^ Callahan MP, Smith KE, Cleaves HJ, Ruzicka J, Stern JC, Glavin DP, House CH, Dworkin JP (August 2011). "Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases". Proceedings of the National Academy of Sciences of the United States of America. 108 (34): 13995–8. Bibcode:2011PNAS..10813995C. doi:10.1073/pnas.1106493108. PMC 3161613 . PMID 21836052.  ^ Steigerwald J (8 August 2011). " NASA
NASA
Researchers: DNA
DNA
Building Blocks Can Be Made in Space". NASA. Archived from the original on 23 June 2015. Retrieved 10 August 2011.  ^ ScienceDaily Staff (9 August 2011). " DNA
DNA
Building Blocks Can Be Made in Space, NASA
NASA
Evidence Suggests". ScienceDaily. Archived from the original on 5 September 2011. Retrieved 9 August 2011.  ^ Marlaire R (3 March 2015). " NASA
NASA
Ames Reproduces the Building Blocks of Life
Life
in Laboratory". NASA. Archived from the original on 5 March 2015. Retrieved 5 March 2015.  ^ Goff SP, Berg P (December 1976). "Construction of hybrid viruses containing SV40 and lambda phage DNA
DNA
segments and their propagation in cultured monkey cells". Cell. 9 (4 PT 2): 695–705. doi:10.1016/0092-8674(76)90133-1. PMID 189942.  ^ Houdebine LM (2007). "Transgenic animal models in biomedical research". Methods in Molecular Biology. 360: 163–202. doi:10.1385/1-59745-165-7:163. ISBN 1-59745-165-7. PMID 17172731.  ^ Daniell H, Dhingra A (April 2002). "Multigene engineering: dawn of an exciting new era in biotechnology". Current Opinion in Biotechnology. 13 (2): 136–41. doi:10.1016/S0958-1669(02)00297-5. PMC 3481857 . PMID 11950565.  ^ Job D (November 2002). " Plant
Plant
biotechnology in agriculture". Biochimie. 84 (11): 1105–10. doi:10.1016/S0300-9084(02)00013-5. PMID 12595138.  ^ Curtis C, Hereward J (29 August 2017). "From the crime scene to the courtroom: the journey of a DNA
DNA
sample". The Conversation. Archived from the original on 22 October 2017. Retrieved 22 October 2017.  ^ Collins A, Morton NE (June 1994). "Likelihood ratios for DNA identification". Proceedings of the National Academy of Sciences of the United States of America. 91 (13): 6007–11. Bibcode:1994PNAS...91.6007C. doi:10.1073/pnas.91.13.6007. PMC 44126 . PMID 8016106.  ^ Weir BS, Triggs CM, Starling L, Stowell LI, Walsh KA, Buckleton J (March 1997). "Interpreting DNA
DNA
mixtures". Journal of Forensic Sciences. 42 (2): 213–22. PMID 9068179.  ^ Jeffreys AJ, Wilson V, Thein SL (1985). "Individual-specific 'fingerprints' of human DNA". Nature. 316 (6023): 76–9. Bibcode:1985Natur.316...76J. doi:10.1038/316076a0. PMID 2989708.  ^ Colin Pitchfork — first murder conviction on DNA
DNA
evidence also clears the prime suspect Forensic Science Service Accessed 23 December 2006 ^ " DNA
DNA
Identification in Mass Fatality Incidents". National Institute of Justice. September 2006. Archived from the original on 12 November 2006.  ^ "Paternity Blood
Blood
Tests That Work Early in a Pregnancy" New York Times June 20, 2012 Archived 24 June 2017 at the Wayback Machine. ^ a b Breaker RR, Joyce GF (December 1994). "A DNA
DNA
enzyme that cleaves RNA". Chemistry & Biology. 1 (4): 223–9. doi:10.1016/1074-5521(94)90014-0. PMID 9383394.  ^ Chandra M, Sachdeva A, Silverman SK (October 2009). "DNA-catalyzed sequence-specific hydrolysis of DNA". Nature Chemical Biology. 5 (10): 718–20. doi:10.1038/nchembio.201. PMC 2746877 . PMID 19684594.  ^ Carmi N, Shultz LA, Breaker RR (December 1996). " In vitro
In vitro
selection of self-cleaving DNAs". Chemistry & Biology. 3 (12): 1039–46. doi:10.1016/S1074-5521(96)90170-2. PMID 9000012.  ^ Torabi SF, Wu P, McGhee CE, Chen L, Hwang K, Zheng N, Cheng J, Lu Y (May 2015). " In vitro
In vitro
selection of a sodium-specific DNAzyme and its application in intracellular sensing". Proceedings of the National Academy of Sciences of the United States of America. 112 (19): 5903–8. Bibcode:2015PNAS..112.5903T. doi:10.1073/pnas.1420361112. PMC 4434688 . PMID 25918425.  ^ Baldi P, Brunak S (2001). Bioinformatics: The Machine Learning Approach. MIT Press. ISBN 978-0-262-02506-5. OCLC 45951728.  ^ Gusfield, Dan. Algorithms on Strings, Trees, and Sequences: Computer Science and Computational Biology. Cambridge University Press, 15 January 1997. ISBN 978-0-521-58519-4. ^ Sjölander K (January 2004). "Phylogenomic inference of protein molecular function: advances and challenges". Bioinformatics. 20 (2): 170–9. doi:10.1093/bioinformatics/bth021. PMID 14734307.  ^ Mount DM (2004). Bioinformatics: Sequence and Genome
Genome
Analysis (2nd ed.). Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press. ISBN 0-87969-712-1. OCLC 55106399.  ^ Rothemund PW (March 2006). "Folding DNA
DNA
to create nanoscale shapes and patterns". Nature. 440 (7082): 297–302. Bibcode:2006Natur.440..297R. doi:10.1038/nature04586. PMID 16541064.  ^ Andersen ES, Dong M, Nielsen MM, Jahn K, Subramani R, Mamdouh W, Golas MM, Sander B, Stark H, Oliveira CL, Pedersen JS, Birkedal V, Besenbacher F, Gothelf KV, Kjems J (May 2009). "Self-assembly of a nanoscale DNA
DNA
box with a controllable lid". Nature. 459 (7243): 73–6. Bibcode:2009Natur.459...73A. doi:10.1038/nature07971. PMID 19424153.  ^ Ishitsuka Y, Ha T (May 2009). " DNA
DNA
nanotechnology: a nanomachine goes live". Nature Nanotechnology. 4 (5): 281–2. Bibcode:2009NatNa...4..281I. doi:10.1038/nnano.2009.101. PMID 19421208.  ^ Aldaye FA, Palmer AL, Sleiman HF (September 2008). "Assembling materials with DNA
DNA
as the guide". Science. 321 (5897): 1795–9. Bibcode:2008Sci...321.1795A. doi:10.1126/science.1154533. PMID 18818351.  ^ Wray GA (2002). "Dating branches on the tree of life using DNA". Genome
Genome
Biology. 3 (1): REVIEWS0001. doi:10.1046/j.1525-142X.1999.99010.x. PMC 150454 . PMID 11806830.  ^ Lost Tribes of Israel, Nova, PBS airdate: 22 February 2000. Transcript available from PBS.org Archived 28 June 2017 at the Wayback Machine.. Retrieved 4 March 2006. ^ Kleiman, Yaakov. "The Cohanim/ DNA
DNA
Connection: The fascinating story of how DNA
DNA
studies confirm an ancient biblical tradition". Archived 25 April 2016 at the Wayback Machine. aish.com (13 January 2000). Retrieved 4 March 2006. ^ Goldman N, Bertone P, Chen S, Dessimoz C, LeProust EM, Sipos B, Birney E (February 2013). "Towards practical, high-capacity, low-maintenance information storage in synthesized DNA". Nature. 494 (7435): 77–80. Bibcode:2013Natur.494...77G. doi:10.1038/nature11875. PMC 3672958 . PMID 23354052.  ^ Naik, Gautam (24 January 2013). "Storing Digital Data in DNA". Wall Street Journal. Archived from the original on 24 January 2015. Retrieved 24 January 2013.  ^ Comment by Dandekar, T., Lopez, D., Schaack, D. (2013) http://www.nature.com/nature/journal/v494/n7435/abs/nature11875.html#comment-57415 Archived 5 October 2016 at the Wayback Machine. ^ Emerging Technology Final, Dandekar T., Lopez, D., Programmable bacterial membranes with active DNA
DNA
storage; presentation for the University of Würzburg for the Royal Society for Chemistry, London, 29 June 2016 ^ Patent "Molecular highly integrated data storage via active control DNA", DE102013004584 A1, "Archived copy". Archived from the original on 30 October 2016. Retrieved 30 October 2016. " ^ Miescher, Friedrich (1871) "Ueber die chemische Zusammensetzung der Eiterzellen" Archived 22 October 2015 at the Wayback Machine. (On the chemical composition of pus cells), Medicinisch-chemische Untersuchungen, 4 : 441–460. From p. 456: Archived 25 September 2015 at the Wayback Machine. "Ich habe mich daher später mit meinen Versuchen an die ganzen Kerne gehalten, die Trennung der Körper, die ich einstweilen ohne weiteres Präjudiz als lösliches und unlösliches Nuclein bezeichnen will, einem günstigeren Material überlassend." (Therefore, in my experiments I subsequently limited myself to the whole nucleus, leaving to a more favorable material the separation of the substances, that for the present, without further prejudice, I will designate as soluble and insoluble nuclear material ("Nuclein").) ^ Dahm R (January 2008). "Discovering DNA: Friedrich Miescher
Friedrich Miescher
and the early years of nucleic acid research". Human Genetics. 122 (6): 565–81. doi:10.1007/s00439-007-0433-0. PMID 17901982.  ^ See:

Albrect Kossel (1879) "Ueber Nucleïn der Hefe" Archived 17 November 2017 at the Wayback Machine. (On nuclein in yeast) Zeitschrift für physiologische Chemie, 3 : 284–291. Albrect Kossel (1880) "Ueber Nucleïn der Hefe II" Archived 17 November 2017 at the Wayback Machine. (On nuclein in yeast, Part 2) Zeitschrift für physiologische Chemie, 4 : 290–295. Albrect Kossel (1881) "Ueber die Verbreitung des Hypoxanthins im Thier- und Pflanzenreich" Archived 17 November 2017 at the Wayback Machine. (On the distribution of hypoxanthins in the animal and plant kingdoms) Zeitschrift für physiologische Chemie, 5 : 267–271. Albrect Kossel, Untersuchungen über die Nucleine und ihre Spaltungsprodukte [Investigations into nuclein and its cleavage products] (Strassburg, Germany: K.J. Trübne, 1881), 19 pages. Albrect Kossel (1882) "Ueber Xanthin und Hypoxanthin" Archived 17 November 2017 at the Wayback Machine. (On xanthin and hypoxanthin), Zeitschrift für physiologische Chemie, 6 : 422–431. Albrect Kossel (1883) "Zur Chemie des Zellkerns" Archived 17 November 2017 at the Wayback Machine. (On the chemistry of the cell nucleus), Zeitschrift für physiologische Chemie, 7 : 7–22. Albrect Kossel (1886) "Weitere Beiträge zur Chemie des Zellkerns" (Further contributions to the chemistry of the cell nucleus), Zeitschrift für Physiologische Chemie, 10 : 248–264. Available on-line at: Max Planck Institute for the History of Science, Berlin, Germany Archived 14 July 2014 at the Wayback Machine.. On p. 264, Kossel remarked presciently: "Der Erforschung der quantitativen Verhältnisse der vier stickstoffreichen Basen, der Abhängigkeit ihrer Menge von den physiologischen Zuständen der Zelle, verspricht wichtige Aufschlüsse über die elementaren physiologisch-chemischen Vorgänge." (The study of the quantitative relations of the four nitrogenous bases — [and] of the dependence of their quantity on the physiological states of the cell — promises important insights into the fundamental physiological-chemical processes.)

^ Jones ME (September 1953). "Albrecht Kossel, a biographical sketch". The Yale Journal of Biology
Biology
and Medicine. National Center for Biotechnology Information. 26 (1): 80–97. PMC 2599350 . PMID 13103145.  ^ Levene P (1919). "The structure of yeast nucleic acid". J Biol Chem. 40 (2): 415–24.  ^ See:

Astbury WT, Bell FO (1938). "Some recent developments in the X-ray study of proteins and related structures" (PDF). Cold Spring Harbor Symposia on Quantitative Biology. 6: 109–121. Archived from the original (PDF) on 14 July 2014.  Astbury WT (1947). " X-ray
X-ray
studies of nucleic acids". Symposia of the Society for Experimental Biology
Biology
(1): 66–76. PMID 20257017. Archived from the original on 5 July 2014. 

^ Koltsov proposed that a cell's genetic information was encoded in a long chain of amino acids. See:

Н. К. Кольцов, "Физико-химические основы морфологии" (The physical-chemical basis of morphology) – speech given at the 3rd All-Union Meeting of Zoologist, Anatomists, and Histologists at Leningrad, U.S.S.R., 12 December 1927. Reprinted in: Успехи экспериментальной биологии (Advances in Experimental Biology), series B, 7 (1) :  ?-? (1928). Reprinted in German as: Nikolaj K. Koltzoff (1928) "Physikalisch-chemische Grundlagen der Morphologie" (The physical-chemical basis of morphology), Biologisches Zentralblatt, 48 (6) : 345–369. In 1934, Koltsov contended that the proteins that contain a cell's genetic information replicate. See: N. K. Koltzoff (5 October 1934) "The structure of the chromosomes in the salivary glands of Drosophila," Science, 80 (2075) : 312–313. From page 313: "I think that the size of the chromosomes in the salivary glands [of Drosophila] is determined through the multiplication of genonemes. By this term I designate the axial thread of the chromosome, in which the geneticists locate the linear combination of genes; … In the normal chromosome there is usually only one genoneme; before cell-division this genoneme has become divided into two strands."

^ Soyfer VN (September 2001). "The consequences of political dictatorship for Russian science". Nature Reviews. Genetics. 2 (9): 723–9. doi:10.1038/35088598. PMID 11533721.  ^ Griffith F (January 1928). "The Significance of Pneumococcal Types". The Journal of Hygiene. 27 (2): 113–59. doi:10.1017/S0022172400031879. PMC 2167760 . PMID 20474956.  ^ Lorenz MG, Wackernagel W (September 1994). "Bacterial gene transfer by natural genetic transformation in the environment". Microbiological Reviews. 58 (3): 563–602. PMC 372978 . PMID 7968924.  ^ Avery OT, Macleod CM, McCarty M (February 1944). "Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III". The Journal of Experimental Medicine. 79 (2): 137–58. doi:10.1084/jem.79.2.137. PMC 2135445 . PMID 19871359.  ^ Hershey AD, Chase M (May 1952). "Independent functions of viral protein and nucleic acid in growth of bacteriophage". The Journal of General Physiology. 36 (1): 39–56. doi:10.1085/jgp.36.1.39. PMC 2147348 . PMID 12981234.  ^ The B- DNA
DNA
X-ray
X-ray
pattern on the right of this linked image Archived 25 May 2012 at Archive.is
Archive.is
was obtained by Rosalind Franklin
Rosalind Franklin
and Raymond Gosling
Raymond Gosling
in May 1952 at high hydration levels of DNA
DNA
and it has been labeled as "Photo 51" ^ Regis, Ed (2009) What Is Life?: investigating the nature of life in the age of synthetic biology. Oxford: Oxford University Press ISBN 0-19-538341-9; p. 52 ^ Nature Archives Double Helix of DNA: 50 Years Archived 5 April 2015 at the Wayback Machine. ^ "Original X-ray diffraction
X-ray diffraction
image". Oregon State Library. Archived from the original on 30 January 2009. Retrieved 6 February 2011.  ^ "The Nobel Prize in Physiology or Medicine
Nobel Prize in Physiology or Medicine
1962". Nobelprize.org.  ^ Maddox B (January 2003). "The double helix and the 'wronged heroine'" (PDF). Nature. 421 (6921): 407–8. Bibcode:2003Natur.421..407M. doi:10.1038/nature01399. PMID 12540909. Archived (PDF) from the original on 17 October 2016.  ^ Crick F (1955). A Note for the RNA
RNA
Tie Club (PDF) (Speech). Cambridge, England. Archived from the original (PDF) on 1 October 2008.  ^ Meselson M, Stahl FW (July 1958). "THE REPLICATION OF DNA
DNA
IN ESCHERICHIA COLI". Proceedings of the National Academy of Sciences of the United States of America. 44 (7): 671–82. Bibcode:1958PNAS...44..671M. doi:10.1073/pnas.44.7.671. PMC 528642 . PMID 16590258.  ^ "The Nobel Prize in Physiology or Medicine
Nobel Prize in Physiology or Medicine
1968". Nobelprize.org.  ^ Pray L (2008). "Discovery of DNA structure
DNA structure
and function: Watson and Crick". Nature Education. 1 (1): 100. 

Further reading

Berry A, Watson J (2003). DNA: the secret of life. New York: Alfred A. Knopf. ISBN 0-375-41546-7.  Calladine CR, Drew HR, Luisi BF, Travers AA (2003). Understanding DNA: the molecule & how it works. Amsterdam: Elsevier Academic Press. ISBN 0-12-155089-3.  Carina D, Clayton J (2003). 50 years of DNA. Basingstoke: Palgrave Macmillan. ISBN 1-4039-1479-6.  Judson HF (1979). The Eighth Day of Creation: Makers of the Revolution in Biology
Biology
(2nd ed.). Cold Spring Harbor Laboratory Press. ISBN 0-671-22540-5.  Olby RC (1994). The path to the double helix: the discovery of DNA. New York: Dover Publications. ISBN 0-486-68117-3. , first published in October 1974 by MacMillan, with foreword by Francis Crick; the definitive DNA
DNA
textbook, revised in 1994 with a 9-page postscript Micklas D (2003). DNA
DNA
Science: A First Course. Cold Spring Harbor Press. ISBN 978-0-87969-636-8.  Ridley M (2006). Francis Crick: discoverer of the genetic code. Ashland, OH: Eminent Lives, Atlas Books. ISBN 0-06-082333-X.  Olby RC (2009). Francis Crick: A Biography. Plainview, N.Y: Cold Spring Harbor Laboratory Press. ISBN 0-87969-798-9.  Rosenfeld I (2010). DNA: A Graphic Guide to the Molecule that Shook the World. Columbia University Press. ISBN 978-0-231-14271-7.  Schultz M, Cannon Z (2009). The Stuff of Life: A Graphic Guide to Genetics
Genetics
and DNA. Hill and Wang. ISBN 0-8090-8947-5.  Stent GS, Watson J (1980). The Double Helix: A Personal Account of the Discovery of the Structure of DNA. New York: Norton. ISBN 0-393-95075-1.  Watson, James (2004). DNA: The Secret of Life. Random House. ISBN 978-0-09-945184-6.  Wilkins M (2003). The third man of the double helix the autobiography of Maurice Wilkins. Cambridge, England: University Press. ISBN 0-19-860665-6. 

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DNA
DNA
at Curlie (based on DMOZ) DNA
DNA
binding site prediction on protein DNA
DNA
the Double Helix Game From the official Nobel Prize web site DNA
DNA
under electron microscope Dolan DNA
DNA
Learning Center Double Helix: 50 years of DNA, Nature Proteopedia DNA Proteopedia Forms_of_DNA ENCODE threads explorer ENCODE home page. Nature Double Helix 1953–2003 National Centre for Biotechnology Education Genetic Education Modules for Teachers— DNA
DNA
from the Beginning Study Guide PDB Molecule of the Month DNA Clue to chemistry of heredity found The New York Times
The New York Times
June 1953. First American newspaper coverage of the discovery of the DNA structure Olby R (January 2003). "Quiet debut for the double helix". Nature. 421 (6921): 402–5. Bibcode:2003Natur.421..402O. doi:10.1038/nature01397. PMID 12540907.  DNA
DNA
from the Beginning Another DNA
DNA
Learning Center site on DNA, genes, and heredity from Mendel to the human genome project. The Register of Francis Crick
Francis Crick
Personal Papers 1938 – 2007 at Mandeville Special
Special
Collections Library, University of California, San Diego Seven-page, handwritten letter that Crick sent to his 12-year-old son Michael in 1953 describing the structure of DNA. See Crick’s medal goes under the hammer, Nature, 5 April 2013.

v t e

Gene
Gene
expression

Introduction to genetics

Genetic code Central dogma

DNA → RNA → Protein

Special
Special
transfers

RNA→RNA RNA→DNA Protein→Protein

Transcription

Types

Bacterial Eukaryotic

Key elements

Transcription factor RNA
RNA
polymerase Promoter

Post-transcription

Precursor m RNA
RNA
(pre-mRNA / hnRNA) 5' capping Splicing Polyadenylation Histone
Histone
acetylation and deacetylation

Translation

Types

Prokaryotic Eukaryotic

Key elements

Ribosome Transfer RNA
RNA
(tRNA) Ribosome-nascent chain complex
Ribosome-nascent chain complex
(RNC) Post-translational modification (functional groups · peptides · structural changes)

Regulation

Epigenetic

imprinting

Transcriptional

Gene
Gene
regulatory network cis-regulatory element

lac operon Post-transcriptional

sequestration (P-bodies) alternative splicing microRNA

Translational Post-translational

reversible irreversible

Influential people

François Jacob Jacques Monod

v t e

Types of nucleic acids

Constituents

Nucleobases Nucleosides Nucleotides Deoxynucleotides

Ribonucleic acids (coding, non-coding)

Translational

Messenger

precursor, heterogenous nuclear

Transfer Ribosomal Transfer-messenger

Regulatory

Interferential

Micro Small interfering Piwi-interacting

Antisense Processual

Small nuclear Small nucleolar Small Cajal Body RNAs Y RNA

Enhancer RNAs

Others

Guide Ribozyme Small hairpin Small temporal Trans-acting small interfering Subgenomic messenger

Deoxyribonucleic acids

Complementary Chloroplast Deoxyribozyme Genomic Multicopy single-stranded Mitochondrial

Analogues

Xeno

Glycol Threose Hexose

Locked Peptide Morpholino

Cloning vectors

Phagemid Plasmid Lambda phage Cosmid Fosmid Artificial chromosomes

P1-derived Bacterial Yeast Human

v t e

Genetics

Introduction Outline History Index

Key components

Chromosome DNA RNA Nucleotide Genome

Fields

Classical Conservation Ecological Immunogenetics Molecular Population Quantitative

Archaeogenetics of

the Americas the British Isles Europe Italy the Near East South Asia

Related topics

Behavioural genetics Epigenetics Geneticist Genomics Genetic code Medical genetics Molecular evolution Reverse genetics Genetic engineering Genetic diversity Heredity Genetic monitoring Genetic genealogy

List of genetics research organizations Genetics

Molecular and cellu

.