The bacterial repair system that corrects mismatched bases after polymerization is able to discriminate between the old and newly made DNA strands because
A) the new strand will contain the incorrect base if a mismatch occurs.
B) the older DNA is more likely to contain errors.
C) the older DNA contains methyl groups at specific sequences.
D) the newer DNA contains methyl groups at specific sequences.
E) the DNA polymerase is attached to the new strand.

Question

Quizplus · Accepted Answer

The bacterial repair system that corrects mismatched bases after polymerization is able to discriminate between the old and newly made DNA strands because the older DNA contains methyl groups at specific sequences, while the newly synthesized DNA does not have these methyl groups. The repair system recognizes the presence of these methyl groups on the older strand and uses this information to distinguish between the two strands.

The Bacterial Repair System That Corrects Mismatched Bases After Polymerization