Question

DNA synthesis has an extraordinary high fidelity: between 10-8 and 10-10

1 error per genome (4,200 kb) per 1000 bacterial replications. (10-6 /gene per generation)

Proofreading function: all bacterial DNA polymerases have a 3'-5' exonuclease activity. Operates in the reverse direction from synthesis.

If No proofreading: Expected error is 1 per ____ bps replicated.

Answer 1

The fidelity of DNA synthesis is maintained by the proofreading function of DNA polymerases, which correct mismatches during replication. Without proofreading, the error rate would increase.

Step-by-step explanation:

The question pertains to the fidelity of DNA synthesis and the proofreading function of DNA polymerases in bacteria. Without the proofreading function provided by the 3'-5' exonuclease activity of bacterial DNA polymerases, the error rate in DNA replication would increase significantly. DNA polymerases are able to correct mismatches by sensing a mismatched base pair, slowing the synthesis process, and then hydrolyzing the incorrect nucleotides until the mismatch is reached and corrected. This exonuclease action corrects the majority of errors during replication, contributing to the high fidelity of the process.