Question

The mismatch repair system recognizes mismatched base pairs, removes a portion of the DNA strand containing the error, and then resynthesizes the missing DNA using the correct sequence as a template. But what if the mismatch repair system instead removed a piece of the DNA strand that contained the correct sequence? What would replication of this improperly repaired sequence produce?
A. two DNA molecules that are missing one nucleotide pair

B. two DNA molecules bearing the same mutation

C. two DNA molecules with a gap where the correct sequence was excised

D. one DNA molecule with a mutation and one DNA molecule with a mismatch

E. two DNA molecules with different mutations

Answer 1

Answer:

B) two DNA molecules bearing the same mutation

Explanation:

The mismatch repair system is the biological system of proofreading the DNA strands which takes place after the DNA replication. The system works by recognizing the mispaired bases which could have added due to the insertion, deletion or any replicative error. The mismatched pair removes the wrong bases and then DNA ligases join the DNA.

If the repair system mistakenly removes the DNA with correct sequence then the DNA replication process would form the two DNA strands with the same type of mutation as the DNA replication forms the complementary strands from the two strands of the parent DNA.

Thus, Option-B is the correct answer.