Q. The number of triplet codons having all the three bases same in 64 triplet codons is :
(a) 2
(b) 4
(c) 6
(d) 8
Solution :
Correct option : B Three is the minimum number of nucleotides per codon needed to encode 20 amino acids. 20 amino acids are encoded by combinations of 3 nucleotides. If a codon were two nucleotides, the set of all combinations could encode only. 4×4 = 16 amino acids. With three nucleotides, the set of all combinations can encode. 4x4x4 = 64 amino acids i.e., 64 different combinations of four nucleotides taken three at a time.