Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during DNA replication?

• A. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
• B. The leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end.
• C. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together.
• D. The leading strand is synthesized at twice the rate of the lagging strand.

Answer: (A)

Verified step by step guidance

1. Understand the process of DNA replication: DNA replication involves the unwinding of the double helix and the synthesis of new complementary strands. This occurs at the replication fork, where the DNA is split into two single strands.
2. Identify the directionality of DNA synthesis: DNA polymerase can only add nucleotides to the 3' end of a growing DNA strand, meaning DNA synthesis occurs in a 5' to 3' direction.
3. Differentiate between the leading and lagging strands: The leading strand is synthesized continuously in the same direction as the replication fork movement, while the lagging strand is synthesized discontinuously in the opposite direction.
4. Recognize the role of Okazaki fragments: On the lagging strand, short DNA segments known as Okazaki fragments are synthesized. These fragments are later joined together by the enzyme DNA ligase to form a continuous strand.
5. Clarify the synthesis rate: Both the leading and lagging strands are synthesized at the same rate, but the lagging strand requires additional steps due to the discontinuous synthesis and joining of Okazaki fragments.