Question

Answer the posted question below. ID the correct answer and provide reasoning. Also, provide reasoning for incorrect answers as well.

26) A class of DNA mutations resulting in multiple contiguous amino acid changes in the encoded corresponding protein is described as “___” mutations

a) frameshift

b) transversion

c) transition

d) base analog

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25) Which of the following is false regarding mis-match repair?

a) It is initiated by specific proteins that function in sequential steps, not as a singular large complex

b) It is the same mechanism as recombination repair

c) It involves DNA ligase

d) It involves DNA polymerase 5’ to 3’ activity

?

Answer 1

26. Option a is the correct answer. Frameshift mutation is caused by insertion or deletion of a number of nucleotides that is not divisible by three and thus the whole reading frame is changed due to triplet nature of codon. Since whole reading frame is changed the amino acid sequence in a protein is completely changed and thus it results in multiple contigous amino acid changes in the encoded corresponding protein. Rest all (transversion, transition and base analog) involves a change in nucleotide sequence at a particular area and thus only those amino acid sequence is changed which are corresponding to that particular nucleotide sequence.

27. Option b is the correct answer. Mismacth repair is a multistep process which involve both DNA ligase to rejoin and DNA polymerase to add new required nucleotide. It does not involve double strand break like in recombination repair.