Final answer:
DNA replication is safeguarded by proofreading by DNA polymerases, mismatch repair mechanisms such as the one involving hemi methylated DNA in E. coli, and the action of DNA ligase to join DNA fragments. These processes ensure a high fidelity of DNA replication with minimal errors.
Step-by-step explanation:
To ensure minimal errors during replication, several sophisticated DNA repair mechanisms and proofreading processes are in place. The primary mechanism for error correction is proofreading by DNA polymerases. These enzymes check each newly added base against the template strand and excise any incorrect base before continuing DNA synthesis.
In addition to proofreading, the mismatch repair system corrects errors immediately after the replication machinery has moved on. For instance, in E. coli, the DNA is recognized as hemimethylated, wherein proteins recognize the non-methylated, newly synthesized strand containing an error. This strand is then excised in the incorrect section and replaced with the correct DNA sequence.
Furthermore, DNA ligase plays a crucial role in the replication process by sealing nicks in the DNA, ensuring a continuous strand. These mechanisms collectively contribute to the high fidelity of DNA replication, making errors rare events within cells.