DNA: Difference between revisions
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<StructureSection load='B-DNA.pdb' size=' | <StructureSection load='B-DNA.pdb' size='450' side='right' scene='DNA/B-dna/7' caption='B-DNA'> | ||
'''Deoxyribonucleic acid''' or '''DNA''' is a molecule which is the carrier of genetic information in nearly all the living organisms. It contains the biological instructions for the development, survival and reproduction of organisms. | '''Deoxyribonucleic acid''' or '''DNA''' is a molecule which is the carrier of genetic information in nearly all the living organisms. It contains the biological instructions for the development, survival and reproduction of organisms. | ||
DNA is found in the nucleus of a cell where it is packaged into a compact form called a chromosome with the help of several proteins known as histones. It is also found in cell structures called mitochondria. However in case of prokaryotes DNA is not enclosed in a nucleus or a membrane but is present in the cytoplasm. The DNA in prokaryotes in generally circular and supercoiled without any histones. DNA stores genetic information as a sequence of nucleotides in special regions known as genes which are used to make proteins. The expression of genetic information into proteins is a two-stage process wherein the sequence of nucleotides in DNA is converted to a molecule called Ribonucleic acid or [[RNA]] by a process called [[transcription]]. RNA is used to make proteins by another process called [[translation]]. The human genome contains nearly 3 · 10<sup>9</sup> bases with around 20,000 genes on 23 chromosomes. <ref name='gene'>http://www.genome.gov/25520880 </ref> | DNA is found in the nucleus of a cell where it is packaged into a compact form called a chromosome with the help of several proteins known as histones. It is also found in cell structures called mitochondria. However in case of prokaryotes DNA is not enclosed in a nucleus or a membrane but is present in the cytoplasm. The DNA in prokaryotes in generally circular and supercoiled without any histones. DNA stores genetic information as a sequence of nucleotides in special regions known as genes which are used to make proteins. The expression of genetic information into proteins is a two-stage process wherein the sequence of nucleotides in DNA is converted to a molecule called Ribonucleic acid or [[RNA]] by a process called [[transcription]]. RNA is used to make proteins by another process called [[translation]]. The human genome contains nearly 3 · 10<sup>9</sup> bases with around 20,000 genes on 23 chromosomes. <ref name='gene'>http://www.genome.gov/25520880 </ref> | ||
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In a <scene name='DNA/Bdnasf/1'>DNA double helix</scene> the <scene name='DNA/Angled_gylcosidic/5'>beta-glycosyl bonds</scene> of bases which are paired <scene name='DNA/Angled_gylcosidic/7'>do not lie opposite</scene> to each other but are positioned at an angle. This results in unequally spaced sugar-phosphate backbones and gives rise to two grooves: the | In a <scene name='DNA/Bdnasf/1'>DNA double helix</scene> the <scene name='DNA/Angled_gylcosidic/5'>beta-glycosyl bonds</scene> of bases which are paired <scene name='DNA/Angled_gylcosidic/7'>do not lie opposite</scene> to each other but are positioned at an angle. This results in unequally spaced sugar-phosphate backbones and gives rise to two grooves: the | ||
<scene name='DNA/Major_groove/2'>major groove</scene> and the <scene name='DNA/Major_groove/7'>minor groove</scene> of different width and depth. The <scene name='DNA/Major_groove/8'>oxygen atoms of the furanose rings</scene> are on the surface of the minor groove, and the major groove is on the opposite side. The floor or surface of major groove is filled with the <scene name='DNA/Major_floor/2'>atoms of the bases</scene>. The larger size of major groove allows for the binding of DNA specific proteins.<ref name="Saenger"> Saenger, Wolfram (1984). ''Principles of Nucleic Acid Structure '' (1st ed). Springer-Verlag. pp. 398. ISBN 0-12-645750-6.</ref><ref name='Watson'> Watson, James D, Nancy H. Hopkins, Jeffrey W. Roberts, Joan Argetsinger Steitz, Alan M.Weiner ''Molecular Biology of Gene'' (4th ed.). The Benjamin/Cummings Publishing Company Inc.pp. 239-249. ISBN 0-8053-9612-8</ref> | <scene name='DNA/Major_groove/2'>major groove</scene> and the <scene name='DNA/Major_groove/7'>minor groove</scene> of different width and depth. The <scene name='DNA/Major_groove/8'>oxygen atoms of the furanose rings</scene> are on the surface of the minor groove, and the major groove is on the opposite side. The floor or surface of major groove is filled with the <scene name='DNA/Major_floor/2'>atoms of the bases</scene>. The larger size of major groove allows for the binding of DNA specific proteins.<ref name="Saenger"> Saenger, Wolfram (1984). ''Principles of Nucleic Acid Structure '' (1st ed). Springer-Verlag. pp. 398. ISBN 0-12-645750-6.</ref><ref name='Watson'> Watson, James D, Nancy H. Hopkins, Jeffrey W. Roberts, Joan Argetsinger Steitz, Alan M.Weiner ''Molecular Biology of Gene'' (4th ed.). The Benjamin/Cummings Publishing Company Inc.pp. 239-249. ISBN 0-8053-9612-8</ref> | ||
== Biological Functions == | == Biological Functions == | ||
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==Forms of DNA== | ==Forms of DNA== | ||
For a comparison of the different forms of DNA, see [[forms of DNA]]. | For a comparison of the different forms of DNA, see [[forms of DNA]]. | ||
== History of DNA Structure == | == History of DNA Structure == | ||
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For more interactive visualizations of DNA, see [http://dna.molviz.org DNA.MolviZ.Org], a tutorial that is available in [http://biomodel.uah.es/model4/dna/ nine languages]. | For more interactive visualizations of DNA, see [http://dna.molviz.org DNA.MolviZ.Org], a tutorial that is available in [http://biomodel.uah.es/model4/dna/ nine languages]. | ||
</StructureSection> | |||
== See Also == | == See Also == | ||
