Genetic Code: the language used to write the instructions for building proteins. (ORNL) 

The sequence of "nucleotides," coded in triplets ... that determines the sequence of "amino acids" in "protein synthesis." A gene's "DNA sequence" can be used to predict the "mRNA" sequence, and the genetic code, in turn, can be used to predict the "amino acid sequence." (HGPIA) A code that specifies the relationship between the sequence of nucleotides in mRNA and the sequence of amino acids in a... (protein). (Brooker, G-15) The genetic code is nearly universal. The DNA of a "bacterium," a human, a corn plant, or a fruit fly is constructed of the same four nucleotides, is assembled in the same structure, and is “replicated” by the same basic mechanism. (Micklos, 120) Only about 3 percent of the human genome is actually used as the set of instructions. These regions are called "coding" regions, and they are scattered throughout the "chromosomes." A coding region contains genes. (NCI16, slide 6) The genetic code reads DNA sequences in groups of three base pairs, which means that a double-stranded DNA molecule can be read in any of six possible "reading frames" - three in the forward direction and three in the reverse. (NHGRI) Also referred to as ‘code script.’


Coding: (processing) the “genetic material” (to) serve as the instructions for protein synthesis. (Micklos, 37) Transcribing DNA into messenger RNA, which is in turn translated into proteins according to the genetic code. (Micklos, 120) To make mRNA using the DNA of a gene as a template. (Then) to convert the mRNA code into a protein. (Batiza, 179) Verb - ‘code.’ Editor’s note - also referred to as ‘genetic coding.’

Codon: a set of three bases. (Batiza, 20) A sequence of three bases on an mRNA molecule which codes for an amino acid. (Indge, 64) Codons function during "translation." (Brooker, G-8) (Francis) Crick suggested that one could read (the genetic) code by following the bases down just one side of the 'DNA ladder.' The first three bases... determine the first type of amino acid at the beginning of the protein. The next three bases, down the side of the DNA ladder in order, without skipping any bases, determine the second type of amino acid in the protein chain, the next three determine the third amino acid, and so on until one reaches a set of three bases that will say 'stop.' (Batiza, 20) Also referred to as 'triplet,' 'nucleotide triplet,' 'triplet code,' and 'reading frame.'

Start Codon: a three-base sequence - usually AUG, that specifies the first amino acid in a polypeptide. (Brooker, G-35) A codon that directs initiation of ("RNA translation") by stimulating the "binding" of "tRNA." (MeSH) Each three-letter codon in the mRNA specifies a particular amino acid. The 'methionine' codon (AUG) is the "start codon" initiating protein synthesis. (ORL) Also referred to as 'initiation codon' and 'start-code sequence.'

Stop Codon: any codon that signals the termination of ("RNA translation.") (MeSH) Three "stop codons" signify the end of a protein sequence. (ORL) Three codons which do not code for an amino acid. Their presence indicates the end of a particular protein. They act as stop signals rather like the presence of a full stop at the end of a sentence. (Indge, 64) One of three-base sequences - UAA, UAG, and UGA - that signals the end of translation. (Brooker, G-35) Also referred to as 'termination codon' and 'stop-code sequence.'

Genetic Code Properties: the genetic code describes the relationship between the sequence of DNA bases (A, C, G, and T) in a gene and the corresponding protein sequence that it encodes. The cell reads the sequence of the gene in groups of three bases. Of the 64 possible combinations of three bases, 61 specify an amino acid, while the remaining three combinations are stop codons. (NHGRI)

Degenerate Code: since there are 20 different amino acids and 64 different codons, an amino acid can be represented by more than one codon. (ORL)

Non-Overlapping Code: each sequence of three bases, codes for a separate amino acid. There is no overlap in the coding sequence. (Indge, 118)

Universal Code: (the genetic code is) universal among all life forms. (ORL) The base sequence ‘CGU’ codes for the amino acid ‘arginine,’ in all "organisms." This property has allowed ‘genetic engineers’ to take a gene from one organism and to insert it into an organism of a completely different species where it will continue to function in exactly the same way. (Indge, 118)