The genetic code can be defined as the set of certain rules using which the living cells translate the information encoded within genetic material (DNA or mRNA sequences) into proteins. The genetic code consists of the sequence of nitrogen bases (A, C, G, U) in an mRNA chain, which are combined in groups of three to form code “words,” called codons. Each codon stands for (encodes) one amino acid, unless it codes for a start or stop signal/04%3A_Molecular_Biology/4.06%3A_Genetic_Code). The genetic code is universal, meaning that virtually all species use the same genetic code for protein synthesis/04%3A_Molecular_Biology/4.06%3A_Genetic_Code). Some key characteristics of the genetic code include:
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Triplet code: A codon or a code word is defined as a group of bases that specify an amino acid. There is strong evidence that a sequence of three nucleotides codes for an amino acid in the protein, i.e., the code is a triplet.
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Non-ambiguous and Universal: Each codon specifies a particular amino acid or a start or stop signal, and the genetic code is universal for all organisms.
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Degenerate code: There are 61 codons for 20 amino acids. But some amino acids are coded by more than one codon. Hence it is said to be degenerated.
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Non-overlapping code: The codons are read in sequence following the start codon until a stop codon is reached/04%3A_Molecular_Biology/4.06%3A_Genetic_Code).
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Commaless: The arrangement of triplet codons on mRNA is one after another without a gap.
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Start and Stop Codons: The start codon is AUG, while UAG, UAA, UGA are the stop or termination codes.
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Polarity: Genetic code could be read only in 5-3 direction on mRNA.
In summary, the genetic code is a set of rules that governs the translation of genetic material into proteins. It consists of codons, which are groups of three nitrogen bases that specify an amino acid or a start or stop signal. The genetic code is universal, non-ambiguous, degenerate, non-overlapping, commaless, and has start and stop codons and polarity.
