Question

How to find number of nucleotide present in gene encoding the protein?

Answer 1

If we assume 1 codon = 1 nucleotide,

20 amino acids require 20 different codons = 20 different nucleotides < 40 different tRNAs.

If we assume 1 codon = 2 nucleotides,

20 amino acids require 20 different codons = 5 x 5 combination of nucleotides? (considering A, T, C, G, U)?

5 x 5 = 25 < 40 different tRNAs.

The correct answer is to consider 1 codon = 2 nucleotides.