Question

If instead of ACT, the first DNA triplet was ACG, which amino acid would be coded for?

Answer 1

Theoretically, it will result in the formation of cysteine or cys. However, in living cell or practically it may not result in formation of cysteine as translation always begins with the formation of methionine which is coded by AUG (start codon) on mRNA.

If DNA contains ACG as the first triplet, then it will be coded as UGC in the mRNA. UGC codes for cysteine which is a semi-essential amino acid.

On the other hand, if ACT is kept as the first triplet in a DNA sequence, then it will be coded as UGA which is one of the three stop codons (UAA, UGA, and UAG).

Answer 2

The answer is cysteine. This is a half essential proteinogenic amino acid with the formulation of HO₂CCHCH₂SH. It is prearranged by the codons UGU and UGC. The thiol side chain in cysteine frequently partakes in enzymatic responses, as a nucleophile.