Question

You have been studying a gene involved in the biosynthesis of histidine and have isolated a number of mutants that do not grow in the absence of exogenous histidine. Cells carrying the first mutation produce a protein ~10% of the size of the wild-type protein. What kinds of mutations could have caused this defect? Select all that apply.

A.Missense Mutation

B.Frameshift Mutation

C.Nonsense Mutation

D.Neutral Mutation

Answer 1

B and C

In the queation, it is given that, the size of mutant protein is less than that of the wild type protein. It means the number of amino acids in the mutant protein is less than that of the wild type protein.

If mis sense mutation would have occured, than only amino acids would have changed. The number of amino acids will remain the same.

If frameshift mutation would have occured, then there is loss or addition of amino acids. If deletion of nucleotides occur, then there will be loss of amino acid(s) or if addition of nucleotodes occur, there is addition of amino acids. If deletion occurs, than size of proteins would decrease.

If non sense mutation would have occured, then it results in formation of a stop codon, leading to premature termination of translation and formation of a truncated peptide. This will also decrease the size of the protein.

If neutral mutation would have occured, then there will be no change in the protein structure and function.

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