Explain two salient features of genetic code.

Explanation

Characters of Genetic code :
1. Genetic code is universal: It means a particular triplet codon codes for same aminoacid in all living organisms.e.g, AUG codes for methionine in all living organisms, plants and animals.
2. Genetic code is triplet in nature: It means set of 3 nucleotides of mRNA will code for one amino acid.
3.Genetic code is degenerative: It means a single aminoacid may be coded by more than one codon. e.g, Leucine is coded by 6 codons such as UUA, UUG, CUU, CUC, CUA and CUG. [In these codons the first two letters of codon and anticodon codes for the same amino acid irrespective, of the 3rd base. This is a wobble hypothesis and this was proposed by Crick. The 3rd base is wobble base]
4. Genetic code is non-overlapping:
When the triplet codons are read from one end of mRNA, they should be read as units of 3 nucleotides. A nucleotide of one codon does not become part of the next codon.
5. Genetic codon has initiator codon: Initiator codon always initiates the protein synthesis and is always AUG. In the absence ofAUG GUG initiates the protein synthesis.
6. Genetic code has terminator codons: These codons do not code for any aminoacids but they terminate or stop the synthesis of polypeptide chain during protein synthesis. They include UAA, UAG UGA.
7. Genetic code is comma, less: It means coding of aminoacid is continuous one after the other during the synthesis of polypeptide chain.
8. Genetic code has co-linearity: The sequence of nucleotides on DNA or mRNA has a relationship with the sequence of aminoacids in a polypeptide chain.