Apolypeptide has the following amino acid sequence: met-ala-gln-arg-glu-leu. this polypeptide was mutated to produce the following mutant sequence: met-ala- gln-gly-glu-leu. which describes the most likely type of mutation that occurred?
a) nonsense mutation
b) missense mutation
c) frameshift mutation
d) loss-of-function mutation
e) neutral mutation

a)A missense mutation has occurred resulting in the substitution of Ser for Pro in the protein. The change is most likely due to a single-base substitution in the Ser codon resulting in the production of a Pro codon. Four of the Ser codons can be changed to Pro codons by a single transition mutation.

b)A single-base substitution has occurred in the Arg codon resulting in the formation of a stop codon. Two of the potential codons for Arg can be changed by single substitutions to stop codons. The phenotypic effect is a nonsense mutation and a shortened protein.

c)The deletion of a single nucleotide at the first position in the Arg codon (most likely CGA) has resulted in a frameshift mutation in which the mRNA is read in a different frame, producing a different amino acid sequence for the protein.

d)A six-base pair deletion has occurred, resulting in the elimination of two amino acids (Arg and Leu) from the protein. This is an in-frame deletion. The result is a truncated polypeptide chain.

e)The addition or insertion of three nucleotides into the DNA sequence has resulted in the addition of a Leu codon to the polypeptide chain. This is an inframe insertion.

Explanation:

a)Mutant 1: Met-Ser-Ser-Arg-Leu-Glu-Gly

b)Mutant 2: Met-Ser-Pro

c) Mutant 3: Met-Ser-Pro-Asp-Trp-Arg-Asp-Lys

d) Mutant 4: Met-Ser-Pro-Glu-Gly

e) Mutant 5: Met-Ser-Pro-Arg-Leu-Leu-Glu-Gly

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion