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Deoxyribonucleic acid (/ d iː ˈ ɒ k s ɪ ˌ r aɪ b oʊ nj uː ˌ k l iː ɪ k,-ˌ k l eɪ-/ ⓘ; [1] DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many ...
Deoxyribonucleic acid (DNA) is a nucleic acid containing the genetic instructions used in the development and functioning of all known living organisms. The chemical DNA was discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. The DNA segments that carry this genetic information are called genes.
When DNA is transcribed to RNA, its complement is paired to it. DNA codes are transferred to RNA codes in a complementary fashion. The encoding of proteins is done in groups of three, known as codons. The standard codon table applies for humans and mammals, but some other lifeforms (including human mitochondria [9]) use different translations. [10]
DNA uses the deoxynucleotides C, G, A, and T, while RNA uses the ribonucleotides (which have an extra hydroxyl(OH) group on the pentose ring) C, G, A, and U. Modified bases are fairly common (such as with methyl groups on the base ring), as found in ribosomal RNA or transfer RNAs or for discriminating the new from old strands of DNA after ...
The sequence of nucleobases on a nucleic acid strand is translated by cell machinery into a sequence of amino acids making up a protein strand. Each group of three bases, called a codon, corresponds to a single amino acid, and there is a specific genetic code by which each possible combination of three bases corresponds to a specific amino acid.
While DNA had been known to biologists since 1869, [2] many scientists still assumed at the time that proteins carried the information for inheritance because DNA appeared to be an inert molecule, and, since it is located in the nucleus, its role was considered to be phosphorus storage.
The simple summary is that DNA makes RNA, and then RNA makes proteins. DNA, RNA, and proteins all consist of a repeating structure of related building blocks (nucleotides in the case of DNA and RNA, amino acids in the case of proteins). In general, they are all unbranched polymers, and so can be represented in the form of a string.
The double-helix model of DNA structure was first published in the journal Nature by James Watson and Francis Crick in 1953, [6] (X,Y,Z coordinates in 1954 [7]) based on the work of Rosalind Franklin and her student Raymond Gosling, who took the crucial X-ray diffraction image of DNA labeled as "Photo 51", [8] [9] and Maurice Wilkins, Alexander Stokes, and Herbert Wilson, [10] and base-pairing ...