Question

A protein with $100$ amino acid residues has been translated based on triplet genetic code. Had the genetic code been quadruplet, the gene that codes for the protein would have been.

• A. Same in size
• B. Longer in size by $25$%
• C. Longer in size by $100$%
• D. Shorter in size

Answer 1

The correct option is B Longer in size by $25$%

Since the genetic code is a triplet, 64 triplets of nucleotides will be involved ( $4^3$ = 64). If the genetic code is quadruplet it consists of 256 triplets of nucleotides ($4^4$ = 256).

64 triplets coded for 100 amino acid residues. So when 256 triplets are involved in coding the genes that codes for the proteins would have been longer in size by 25%.

Calculation-

(100x 256)/64= 400 amino acids.

Hence the percent change will be (100/400) x100= 25%

Thus the correct answer is option B.