Final answer:
The mismatch repair system enhances the fidelity of DNA replication, decreasing the error rate by a 100-fold from the errors introduced by DNA polymerase, which are 1 in 10⁷ nucleotides.
Step-by-step explanation:
The mismatch repair system significantly decreases the error rate arising from DNA replication by a factor of 100-fold. While DNA polymerase introduces errors at a rate of 1 per 10⁷ nucleotides, the mismatch repair mechanism is an additional layer of correction that takes place after DNA replication. This system involves repair enzymes that recognize and excise the incorrectly paired nucleotides that escaped the proofreading function of DNA polymerase. Once the incorrect base has been identified and removed, the correct base is synthesized in its place.
Mismatch repair is crucial in maintaining the integrity of the DNA sequence. Without it, the error rate would be significantly higher, possibly leading to mutations that can have detrimental effects on the organism, including the development of diseases such as cancer. Thus, the correction of errors by mismatch repair enzymes greatly enhances the overall fidelity of DNA replication and maintains genomic stability.
Although DNA polymerase has a proofreading function that helps correct mistakes during replication, it still introduces errors in the newly synthesized strand at a rate of 1 per 10⁷ nucleotides. However, the mismatch repair system steps in to further decrease this error rate. Mismatch repair enzymes recognize wrongly incorporated bases and excise them from the DNA, replacing them with the correct bases. This process reduces the error rate by 100-fold, making DNA replication more accurate.