Chapter 12, Problem 23PDQ

Shown in this problem are the amino acid sequences of the wild type and three mutant forms of a short protein.

(a) Using Figure 12–7, predict the type of mutation that created each altered protein.

(b) Determine the specific ribonucleotide change that led to the synthesis of each mutant protein.

(c) The wild-type RNA consists of nine triplets. What is the role of the ninth triplet?

(d) For the first eight wild-type triplets, which, if any, can you determine specifically from an analysis of the mutant proteins? In each case, explain why or why not.

(e) Another mutation (mutant 4) is isolated. Its amino acid sequence is unchanged, but mutant cells produce abnormallylow amounts of the wild-type proteins. As specifically as you can, predict where this mutation exists in the gene.

Wild type:	met-trp-tyr-arg-gly-ser-pro-thr
Mutant 1:	met-trp
Mutant 2:	met-trp-his-arg-gly-ser-pro-thr
Mutant 3:	met-cys-ile-val-val-val-gln-his