IMPORTANT FEAUTURES OF GENETIC CODE

Here are some important features of genetic code :

1. sixty one codons correspond to amino acids.
2. Four codons are the signals. There are three stop codons (UAA, UAG, UGA) and one start codon (AUG). Rarely, GUG also acts as start codon.
3. Amino acids with similar structural property consist of related codons, therefore the aspartic acid codons (GAU and GAC) are related to glutamic acid codons (GAA and GAG). Similarly, the codons of phenylalanine (UUU, UUC), tyrosine (UAU, UAC) and tryptophan (UGG) start with uracil. This characteristic of codons facilitates to minimize the effects of mistakes arising during translation or mutagenic base substitution.
4. For many synonym codons specifying the same amino acid the first two bases of the triplet are constant while the third varies. For example, all the codons starting with CC (CCU, CCC, CCG) specify praline, and all codons starting with AC (ACU, ACC, ACA,ACG) specify threonine. The flexibility in third codon may be to minimize errors.