10. The amino acid sequence of a wildtype peptide and three mutant peptides are

Question

10. The amino acid sequence of a wildtype peptide and three mutant peptides are given. The amino-terminal amino acid is written on the left. Wildtype Met Trp Asp Gin Leu Tyr Mutant 1 Met Trp Asp Gin Val Tyr Mutant 2 Met Trp Asp Mutant 3 Met Trp Gly Ser Thr Val Leu Met His Lys Describe the gene mutations that occurred to produce each mutant peptide (2 points each -6 points) b. Which mutant is most likely to be neutral, that is, have litlefecet on phenotype? Explain. (2 points) c. Give the nucleotide sequence of the coding region of the wildtype mRNA, including the stop codon. Use "N" when any base can be present. If two bases might be present, list both, for example "A/G (4 polnts)

Explanation / Answer

Ans a)

Mutant 1 – In this we see that Leu is replaced by Val and this is a type of substitution mutation. It is a situation where one base is exchanged for another. The change in the codon to another leads to replacement of one amino acid to another where a different amino acid is introduced and makes a small change in the protein produced.

Mutant 2 –Substitution mutation – In this we see that there is abrupt stopping of the sequence formation and this might be due to incorporation of a stop codon.

Mutant 3 – Insertion mutation – In this type of mutation there are extra base pairs that are inserted into the new place.

Ans b) The first type of mutation is likely to have least impact on the phenotype as there is replacement of only one amino acid. Due to replacement of one amino acid by another, it might lead to an minute or not much impactful phenotype

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