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DNA

DNA

A Molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses.

DNA components

Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids; alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life. The two DNA strands are also known as polynucleotides as they are composed of simpler monomeric units called nucleotides. 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 DNA, the pyrimidines are thymine and cytosine; the purines are adenine and guanine. Both strands of double-stranded DNA store the same biological information. This information is replicated as and when the two strands separate.

A large part of 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 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 genetic information. RNA strands are created using DNA strands as a template in a process called transcription. Under the genetic code, these RNA strands specify the sequence of amino acids within proteins in a process called translation. Within eukaryotic cells, DNA is organized into long structures called chromosomes. Before typical cell division, these chromosomes are duplicated in the process of DNA replication, providing a complete set of chromosomes for each daughter cell. Eukaryotic organisms (animals, plants, fungi and protists) store most of their DNA inside the cell nucleus as nuclear DNA, and some in the mitochondria as mitochondrial DNA, or in chloroplasts as chloroplast DNA. In contrast, prokaryotes (bacteria and archaea) store their DNA only in the cytoplasm, in circular chromosomes. Within eukaryotic chromosomes, chromatin proteins, such as histones, compact and organize DNA. These compacting structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.

DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin. 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 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 and DNA-based hybrid materials.

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By MARK THIESSEN
December 2, 2021
AP NEWS
ANCHORAGE, Alaska (AP) -- The remains of a man found on Fire Island just west of Anchorage in 1989 have been identified through DNA and genome sequencing, Alaska State Troopers said Wednesday.Troopers said the victim was Michael Allison Beavers, who owned an excavation business in Chugiak.
By MARK THIESSEN
October 22, 2021
AP NEWS
ANCHORAGE, Alaska (AP) -- A woman known for 37 years only as Horseshoe Harriet, one of dozen or so victims of a notorious Alaska serial killer, has been identified through genetic genealogy and a DNA match, authorities said Friday.
October 8, 2021
AP NEWS
SIOUX FALLS, S.D. (AP) -- A South Dakota woman was convicted of manslaughter Friday in the death of her newborn son whose body was discovered in a ditch 40 years ago. Theresa Bentaas, 60, of Sioux Falls, entered an Alford plea to first-degree manslaughter in an agreement with prosecutors in which they dropped two murder charges, the Argus Leader reported.
John Timmer
September 29, 2021
Ars Technica
Avoiding tests means avoiding treatment, and that means further infections.
John Timmer
September 22, 2021
Ars Technica
Figuring out people's movement across the Pacific is not a simple thing.
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