Final answer:
The growing DNA strand during replication is synthesized in the 5' to 3' direction, as DNA polymerase can only add nucleotides to the 3' end of the strand. The leading strand is synthesized continuously towards the replication fork, while the lagging strand is synthesized in Okazaki fragments away from the fork.
Step-by-step explanation:
The growing strand of DNA during replication is synthesized in the 5' to 3' direction. This occurs because DNA polymerase can only add nucleotides to the 3' end of the new strand. The leading strand, which is synthesized continuously towards the replication fork, is formed in the 5' to 3' direction. In contrast, the lagging strand is synthesized in short segments, known as Okazaki fragments, in the direction away from the replication fork and these are also joined together in the 5' to 3' direction.