Why is the lagging strand synthesized discontinuously during DNA replication?

• A. Because DNA polymerase can synthesize DNA in both 5' to 3' and 3' to 5' directions.
• B. Because the lagging strand is synthesized faster than the leading strand.
• C. Because DNA polymerase can only synthesize DNA in the 5' to 3' direction.
• D. Because the lagging strand is shorter than the leading strand.

Answer: (C)

Verified step by step guidance

1. Understand that DNA replication involves the synthesis of a new DNA strand complementary to the template strand.
2. Recognize that DNA polymerase, the enzyme responsible for synthesizing new DNA, can only add nucleotides in the 5' to 3' direction.
3. Identify that the DNA double helix is antiparallel, meaning one strand runs 5' to 3' and the other runs 3' to 5'.
4. Realize that the leading strand is synthesized continuously in the 5' to 3' direction as the replication fork opens.
5. Understand that the lagging strand, running 3' to 5', must be synthesized in short segments called Okazaki fragments, which are later joined together, because DNA polymerase can only synthesize in the 5' to 3' direction.