AP BIOLOGY

Detailed explanation-1: -All known DNA polymerases add a deoxyribonucleoside 5′-triphosphate to the 3′ hydroxyl group of a growing DNA chain (the primer strand).

Detailed explanation-2: -For example, DNA polymerase III does most of the elongation work, adding nucleotides one by one to the 3’ end of the new and growing single strand.

Detailed explanation-3: -DNA polymerase III starts adding nucleotides to the 3’-OH end of the primer. Elongation of both the lagging and the leading strand continues. RNA primers are removed by exonuclease activity. Gaps are filled by DNA pol I by adding dNTPs.

Detailed explanation-4: -True. DNA polymerase III can only add nucleotides to the 3’ end of a new DNA strand. Because the two parental DNA strands of a double helix are antiparallel (go from 3’ to 5’ in opposite directions), the direction that DNA pol III moves on each strand emerging from a single replication fork must also be opposite.