Question

Even though DNA polymerase has a proofreading function, it still introduces errors in the newly synthesized strand at a rate of 1 per 107 nucleotides. To what degree does the mismatch repair system decrease the error rate arising from DNA replication?

1) 2-fold
2) 5-fold
3) 10-fold
4) 100-fold

Answer 1

The mismatch repair system improves the fidelity of DNA replication by correcting errors not caught by the proofreading function of DNA polymerase. It reduces the error rate by an additional 100-fold, making the overall error rate 1 per 10^9 nucleotides. The correct option is 4) 100-fold

Step-by-step explanation:

The mismatch repair system significantly decreases the error rate that arises from DNA replication. Even though DNA polymerase introduces errors at a rate of 1 per 107 nucleotides and has a proofreading function to correct many of these errors, some may still remain.

It is the mismatch repair mechanism that comes into play after replication is completed to further reduce these errors. This system can recognize and repair incorrectly paired nucleotides, excising the wrong nucleotide and inserting the correct one in its place.

The mismatch repair improves the fidelity of DNA replication by an additional 100-fold, effectively lowering the overall error rate to 1 per 109 nucleotides. The correct option is 4) 100-fold