Question

explain what is meant by the statement the genetic code is degenerate . why is it advantageous for the code to be degenarate?

Answer 1

Genetic code consists of four nucleotides i.e. Adenine, Uracil, Cytosine and Guanine.

The arrangement of these nucleotides determine the genetic code.

These 4 nucleotides codes for 20 different amino acids. These 4 nucleotides Exists in thr form of triplet and each triplet codes of an amino acid.

Suppose there will be 2 nucleotides per codon,, then there will be only 16 types of codons will be possible, which is lower than 20 amino acids.

Also if there will be 4 nucleotides per codon then, there will be 256 possible codons which is much higher than 20 amino acids

Thus, a codon has 3 nucleotides,, then there will be 64 types of codons possible for 20 amino acids.

Now, since codons number is larger than than the number of amino acids. So, one amino acid may be coded by one or more than one amino acid. This is known as degeneracy of the genetic code, where the one amino aicd is coded by more than one amino acid .

Example - ACA, ACU, ACG and ACC these all condons codes for threonine.

Benefits of degenrency of genetic code -

1. It allows to accomodate the 64 types of codons which codes for only 20 amino acids. That is one amino acid can be coded by more than one codon.

2. It reduces the chance of mutation by silent mutation. For example - If the originals sequence has ACG which codes for threonine, somehow it is mutated to ACC which also codes for threonine, then there will be no change in the amino acid and thus ni change in the biological and chemical properties. Thus, this mutation is known as silent mutation. This mutation is overcomed due to the degeneracy of the amino acid.