Question

Which of the following statements is correct?

A. Each nondegenerate site counts as one non synonymous site

B. Each fourfold degenerate site count as one synonymous site

C. Each twofold degenerate site counts as one nonsynonymous site and as one one synonymous

D. All of the above

Answer 1

Answer-

According to the given question-

We know that macromolecules such as DNA , RNA and proteins are made up of subunits and the subunit determine its information and function and these sequence changes through time and this study is called molecular evolution.

synonymous substitution does not changes the changes the amino acid replacement and occur at third codon position. while non synonymous substitution occur at first and second codon position and results in amino acid replacement and causes large variation in different proteins.  

synonymous nucleotide site is four fold degenerate site at which same amino acid is specified but the identity of nucleotide is two fold degenerate site.

Here pyrimidines Y = U or C and purine R = A or G.

The synonymous codon with N are known as four fold degenerate site and those with Y or R are called two fold degenerate site

So considering options -

Each nondegenerate site counts as one non synonymous site - true

Each four fold degenerate site count as one synonymous site - true

Each two fold degenerate site counts as one nonsynonymous site and one synonymous - True

All are true.

so the correct answer is (D)