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Genetic Code is Triplet Code

	Genetic Code is Triplet Code - DNA contains four kinds of nucleotides (of A, T, G and C), and proteins are synthesized from 20 different types of amino acids. A basic problem regarding the genetic code was: how many bases of DNA specify one amino acid? In a singlet code each base or letter would specify one amino acid. Only 4 of the 20 types of amino acids would be coded unambiguously by a singlet code. In a two letter or doublet code two bases would specify one amino acid. Here 16 (4 x 4) of the 20 amino acids can be specified, but there would be ambiguous determination of a number of amino acids.
A triplet or three letter code was first suggested by the physicist Gamow in 1954. According to the triplet code three letters or bases specify one amino acid. Thus 64 (4 x 4 x 4) distinct triplets of purine and or pyrimidine bases determine the 20 amino acids. These triplets have been called codons. Since there are 64 codons and only 20 amino acids it is obvious that there are many more co dons than there are amino acids, i.e. the code is degenerate
Experimental evidence shows that the code is a triplet one and that 61 of the 64 codons code for individual amino acids during protein synthesis. A quadruplet code would have 4x4x4x4 = 256 codons, and would show even more degeneracy than the triplet code.

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Third Base Deciphering the Code Use of Polymer Containing a Single Type of Nucleotide (Homopolymers) Use of Mixed Polymers with Random Sequences (Heteropolymers) Use of Mixed Polymers with Defined Sequences (Heteropolymers) Use of Trinucleotides in Filter Binding (Minimessengers) Genetic Code is Universal Colinearity of Gene Structure and its Polypeptide Product

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