Question

A particular protein has the following amino acid sequence within its primary structure (N . . . Ala-Pro-His-Trp-Arg-Lys-Gly-Val-Thr . . . C). A geneticist studying mutations affecting this protein discovered that several of the mutants produced shortened protein molecules that terminated within this region. In one of them, the His became the terminal amino acid. What DNA single-base change(s) would cause the protein to terminate at the His residue? What other potential sites do you see in the DNA sequence encoding this protein where mutation of a single base pair would cause premature termination of translation

Answer 1

When last G changes to A in tryptophan,it becomes stop codon. Lys,Arg and Gly can be potential sites for termınation.

Explanation:

If his is terminal aminoacid, Trp becomes stop codon. Trp= UGG UGA= stop codon. If last G changes to A, it will become stop codon. Lysine(AAA,AAG) and arginine(CGA,AGA) can be stop codon by changing first base pair from A/C to U. Glycine(GGA) can be stop codon by changing first base G to U. Stop codons are UGA,UAA,UAG.