Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance1 Mark
MCQ
The number of triplet codons having all the three bases same in $64$ triplet codons is:
A
$2$
✓
$4$
C
$6$
D
$8$
✓
Answer
Correct option: B.
$4$
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. $4 \times 4= 16$ amino acids. With three nucleotides, the set of all combinations can encode. $4 \times 4 \times 4 = 64$ amino acids i.e., $64$ different combinations of four nucleotides taken three at a time.
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