Question

A protein molecule consists of the sequence alanine, leucine, tyrosine, serine, leucine. What sequence of mRNA codons would be responsible for forming this protein?

Answer 1

Ans:- The actual sequence of the mRNA is very difficult to tell from given amino acid sequence. Because, you know the phenomena of degeneracy of genetic code means more than one codon codes for a single amino acids. Degeneracy of genetic code protect us from mutation like silent mutation where DNA is changed but protein sequences remians same. So, alanine is coded by GCU, GCC, GCA, and GCG.

Leucine is coded by CUU, CUC, CUA, CUG, UUA and UUG.

Tyrosine is coded by UAU and UAC.

Serine is coded by UCU, UCC, UCA and UCG.

So, for mRNA sequence corresponding to mentioned amino acid I will pick only one codon (first one) for one amino acid.

Thus, the amino acid sequence

Ala- Leu-Tyr-Ser-Leu is encoded by mRNA

5'- GCU CUU UAU UCU CUU-3'

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