Final answer:
The Mismatch Repair System (MMR) corrects DNA replication errors including incorrect pairings such as dTMP with dCMP, dGMP with dAMP, and dAMP with dTMP. It does this by excising the wrongly added nucleotide and replacing it with the correct one, maintaining the fidelity of DNA replication.
Step-by-step explanation:
The Mismatch Repair System (MMR) is responsible for correcting errors that arise during DNA replication. This system recognizes and repairs mispaired but normal, non-damaged nucleotides. The nucleotide pairings that MMR would recognize and correct during DNA replication are dTMP and dCMP, dGMP and dAMP, and dAMP and dTMP. These pairings are incorrect because they do not follow the standard base pairing rules where adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).
MMR works by excising the incorrectly added nucleotide and then filling in the correct nucleotide. The enzymes involved, such as Muts, MutL, and MutH in E. coli, recognize the erroneous base due to the lack of methylation on the newly synthesized strand. This way, they ensure high fidelity of the DNA replication process by preventing permanent mutations that would be propagated if the mismatch were left uncorrected.