(a) What is a genetic code?
(b) Explain the following:
Degenerate code; Unambiguous code; Universal code; Initiator code.
(a) A triplet nitrogenous base sequence on DNA is called genetic code. It is the
relationship between the sequence of nucleotides on mRNA and sequence of
amino acids in the polypeptide.
(b) One codon codes for only one amino acid, hence is unambiguous and specific.
For example, AUG for methionic, UUU for phenylalanine etc.
Some amino acids are coded by more than one codon. Hence the code is degenerate.
The code is nearly universal. For example, bacteria to human UUU would code for 'Phe'.
AUG has dual functions. It codes for methionine (Met) and it also acts as initiator codon.