Which strand of DNA allows DNA polymerase and helicase to work in the same direction?

The leading strand is the correct choice because it is synthesized continuously in the same direction as the movement of the replication fork. During DNA replication, helicase unwinds the double helix, creating two single strands: one for continuous replication and one that is replicated in fragments. On the leading strand, DNA polymerase can add nucleotides in a 5' to 3' direction, following helicase as it unwinds the DNA.

In contrast, the lagging strand grows in the opposite direction of the replication fork, requiring the synthesis of short fragments known as Okazaki fragments, which are later joined together. This means that helicase and DNA polymerase on the lagging strand are not working in the same direction. The codon strand typically refers to the strand that contains the codons for protein synthesis and is not directly involved in the replication process. The template strand conceptually refers to the original strand that guides the synthesis of the new strand but does not specifically indicate the direction of synthesis relative to helicase. Thus, the leading strand is distinct in that it allows for the simultaneous activity of both enzymes in the same direction.