Which pattern of synthesis characterizes the leading strand?

Which pattern of synthesis characterizes the leading strand?

• A. Discontinuous synthesis
• B. Continuous synthesis
• C. No synthesis
• D. Random synthesis

Answer: (B)

Leading strand synthesis is continuous because DNA polymerase can only add nucleotides in the 5' to 3' direction, and the template for this strand runs 3' to 5' toward the replication fork. As the DNA unwinds, a single RNA primer allows DNA polymerase to extend the new strand in one uninterrupted run all the way toward the fork. The lagging strand, opposite in orientation, must be made in short fragments (Okazaki fragments) because polymerase must repeatedly re-prime as the fork progresses. So continuous synthesis best describes the leading strand, while discontinuous synthesis describes the lagging strand. No synthesis or random synthesis would not reflect the observed, regulated directionality of replication.

Leading strand synthesis is continuous because DNA polymerase can only add nucleotides in the 5' to 3' direction, and the template for this strand runs 3' to 5' toward the replication fork. As the DNA unwinds, a single RNA primer allows DNA polymerase to extend the new strand in one uninterrupted run all the way toward the fork. The lagging strand, opposite in orientation, must be made in short fragments (Okazaki fragments) because polymerase must repeatedly re-prime as the fork progresses. So continuous synthesis best describes the leading strand, while discontinuous synthesis describes the lagging strand. No synthesis or random synthesis would not reflect the observed, regulated directionality of replication.