Final answer:
The possible mechanisms of mutagenesis via AID activity include the lesion not being repaired prior to replication, base excision repair followed by error-prone DNA polymerase fill-in of the gap, and mismatch repair followed by error-prone DNA polymerase fill-in of the gap.
Step-by-step explanation:
The possible mechanism of mutagenesis via AID activity includes:
Choice A: The lesion is not repaired prior to replication, resulting in a CG→TA transition. This means that the damaged DNA is replicated without being repaired, leading to a change in the nucleotide sequence. An example of this is the formation of pyrimidine dimers due to UV radiation, which can lead to CG→TA transitions.
Choice B: Base excision repair, followed by error-prone DNA polymerase fill-in of the gap created. In this mechanism, damaged bases are recognized and removed by DNA glycosylases through base excision repair. After the damaged base is removed, an error-prone DNA polymerase fills in the gap with nucleotides. This can introduce mutations during replication.
Choice C: Mismatch repair, followed by error-prone DNA polymerase fill-in of the gap created. Mismatch repair is a process that corrects mismatches in the DNA sequence after replication. However, if the repair is not accurate, an error-prone DNA polymerase can introduce mutations during the fill-in of the gap created.
Therefore, choices A, B, and C are all possible mechanisms of mutagenesis via AID activity.