In DNA replication, in which direction does DNA polymerase synthesize the new DNA strand?

• A. In the same direction on both strands relative to the replication fork, so both are synthesized continuously
• B. $3\prime$ to $5\prime$
• C. $5\prime$ to $3\prime$
• D. Bidirectionally from the origin without a defined strand synthesis direction

Answer: (C)

Verified step by step guidance

1. Recall that DNA strands are antiparallel, meaning one strand runs 5' to 3' and the complementary strand runs 3' to 5'.
2. Understand that DNA polymerase can only add nucleotides to the 3' end of a growing DNA strand, which means synthesis occurs in the 5' to 3' direction.
3. Recognize that during replication, the new strand is synthesized continuously on the leading strand and discontinuously on the lagging strand, but both are synthesized in the 5' to 3' direction relative to the new strand.
4. Note that the direction of synthesis is always away from the 3' end of the template strand, so the polymerase moves along the template strand in the 3' to 5' direction.
5. Conclude that DNA polymerase synthesizes the new DNA strand in the 5' to 3' direction, regardless of the strand being replicated.