Functions of codons

Question

As among the 64 codons of mRNA, 61 codify amino acids which form polypeptide chains. Describe the functions of the three remaining codons?

Answer 1

As there are 20 amino acids and 64 possibilities of mRNA codons, this is predicted some amino acids to be codified by more than one codon. And that actually happens. Not all 64 codons though codify amino acids. Three of them, UAA, UGA and UAG, work on information which the last amino acid of a polypeptide chain beneath productions was already bound, that is, they signal the end of the polypeptide synthesis. Such codons are termed as terminal codons. The codon AUG codifies the amino acid methionine and at similar time it signals the starting of the synthesis of a polypeptide chain (that is, it is an initialization codon).

In prokaryotic cells there is a series termed as Shine-Dalgarno sequence (in common AGGAGG) in the place that antecedes the initialization codon AUG.

The function of this sequence is distinctness among the initialization AUG and other AUG codons of RNA.