genetic code

genetic code
the biochemical instructions that translate the genetic information present as a linear sequence of nucleotide triplets in messenger RNA into the correct linear sequence of amino acids for the synthesis of a particular peptide chain or protein. Cf. codon, translation (def. 9).
[1960-65]

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Sequence of nucleotides in DNA and RNA that determines the amino acid sequence of proteins.

A messenger RNA molecule synthesized from the DNA directs the synthesis of the protein. Three adjacent nucleotides constitute a unit known as a codon; each codon codes for a single amino acid. There are 64 possible codons, 61 of which specify the 20 amino acids that make up proteins. Because most of the 20 amino acids are coded for by more than one codon, the code is called degenerate. Once thought to be identical in all forms of life, the genetic code has been found to vary slightly in certain organisms and in the mitochondria of some eukaryotes.

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 the sequence of nucleotides (nucleotide) in deoxyribonucleic acid (DNA) (DNA) and ribonucleic acid (RNA) (RNA) that determines the amino acid sequence of proteins. Though the linear sequence of nucleotides in DNA contains the information for protein sequences, proteins are not made directly from DNA. Instead, a messenger RNA (mRNA) molecule is synthesized from the DNA and directs the formation of the protein. RNA is composed of four nucleotides: adenine (A), guanine (G), cytosine (C), and uracil (U). Three adjacent nucleotides constitute a unit known as the codon, which codes for an amino acid. For example, the sequence AUG is a codon that specifies the amino acid methionine. There are 64 possible codons, three of which do not code for amino acids but indicate the end of a protein. The remaining 61 codons specify the 20 amino acids that make up proteins. The AUG codon, in addition to coding for methionine, is found at the beginning of every mRNA and indicates the start of a protein. Because most of the 20 amino acids are coded for by more than one codon, the code is called degenerate.

      The genetic code, once thought to be identical in all forms of life, has been found to diverge slightly in certain organisms and in the mitochondria of some eukaryotes. Nevertheless, these differences are rare, and the genetic code is identical in almost all species, with the same codons specifying the same amino acids. The deciphering of the genetic code was accomplished by the American biochemists Marshall W. Nirenberg (Nirenberg, Marshall Warren), Robert W. Holley (Holley, Robert William), and Har Gobind Khorana (Khorana, Har Gobind) in the early 1960s.

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Universalium. 2010.

Look at other dictionaries:

  • genetic code — genetic code. См. генетический код. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Genetic code — A series of codons in part of a messenger RNA (mRNA) molecule. Each codon consists of three nucleotides, usually representing a single amino acid. The nucleotides are abbreviated with the letters A, U, G and C. This is mRNA, which uses U (uracil) …   Wikipedia

  • Genetic code — The instructions in a gene that tell the cell how to make a specific protein. A, T, G, and C are the letters of the DNA code. They stand for the chemicals adenine, thymine, guanine, and cytosine, respectively, that make up the nucleotide bases of …   Medical dictionary

  • genetic code — Genetic information that is encoded into DNA and transcribed to messenger RNA which forms peptides by genetic translation …   Dictionary of invertebrate zoology

  • genetic code — (Roget s IV) n. Syn. genetic alphabet, ribonucleic acid, RNA, language of heredity, adenine, thymine, guanine, cytosine, base pairing; see also DNA …   English dictionary for students

  • genetic code — noun the means by which DNA and RNA molecules carry genetic information in living cells …   English new terms dictionary

  • genetic code — ge.netic code n the arrangement of ↑genes that controls the way a living thing develops …   Dictionary of contemporary English

  • genetic code — ge,netic code noun count the arrangement of genes that makes an individual develop in a particular way …   Usage of the words and phrases in modern English

  • genetic code — noun Date: 1961 the biochemical basis of heredity consisting of codons in DNA and RNA that determine the specific amino acid sequence in proteins and appear to be uniform for nearly all known forms of life …   New Collegiate Dictionary

  • genetic code — Relationship between the sequence of bases in nucleic acid and the order of amino acids in the polypeptide synthesized from it. A sequence of three nucleic acid bases (a triplet) acts as a codeword (codon) for one amino acid …   Dictionary of molecular biology

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