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Which one of the following triplet codes is correctly matched with its specificity for an amino acid in protein synthesis or as 'start' or 'stop' codon : -
A
UCG – Start
B
UUU – Stop
C
UGU – Leucine
D
UAC – Tyrosine
Detailed Solution
UCG codes for serine. The start codon is AUG (methionine). So 'UCG – start' is wrong.
UUU codes for phenylalanine (the first codon deciphered by Nirenberg). The stop codons are UAA, UAG and UGA. So 'UUU – stop' is wrong.
UGU codes for cysteine. Leucine is coded by UUA, UUG and CUU, CUC, CUA, CUG. So 'UGU – leucine' is wrong.
UAC (and UAU) codes for tyrosine. Correctly matched.
So the correct match is UAC – tyrosine.
UUU codes for phenylalanine (the first codon deciphered by Nirenberg). The stop codons are UAA, UAG and UGA. So 'UUU – stop' is wrong.
UGU codes for cysteine. Leucine is coded by UUA, UUG and CUU, CUC, CUA, CUG. So 'UGU – leucine' is wrong.
UAC (and UAU) codes for tyrosine. Correctly matched.
So the correct match is UAC – tyrosine.