Final Answer:
When a mismatched base pair is present in the polymerase active site: The primer:template junction is destabilized, creating several base pairs of unpaired DNA. Therefore the correct option is 2) The primer:template junction is destabilized, creating several base pairs of unpaired DNA.
Step-by-step explanation:
When a mismatched base pair is present in the polymerase active site, the primer:template junction is destabilized. This destabilization occurs because the polymerase recognizes the mismatch and may struggle to maintain a stable interaction between the primer and template strands. As a result, unpaired DNA bases are created in the primer:template junction.
Mismatched base pairs can lead to structural instability in the DNA strand being synthesized. The polymerase may attempt to correct the error by proofreading and repairing the mismatched base pair, but in the process, the destabilization of the primer:template junction may persist. This recognition and repair mechanism is essential for maintaining the integrity of the DNA sequence and preventing the propagation of errors during DNA replication.
In summary, the correct answer (Option 2) reflects the dynamic nature of the primer:template junction when a mismatched base pair is present in the polymerase active site. The destabilization of the junction and the creation of unpaired DNA bases underscore the importance of accurate base pairing during DNA replication and the molecular mechanisms involved in error correction.