Final answer:
The top strand being synthesized by DNA polymerase is built in the 5' to 3' direction, so its 3' end is at the site of nucleotide addition, and its 5' end is opposite. The bottom template strand has the 5' end aligned with the 3' end of the top strand and the 3' end aligned with the 5' end of the top strand.
Step-by-step explanation:
During DNA replication, two strands of DNA serve as templates for building complementary strands. The enzyme DNA polymerase synthesizes new DNA strands by adding nucleotides only in the 5' to 3' direction. Considering the antiparallel nature of DNA, the template strand must be read in the 3' to 5' direction. As such, for the top strand being synthesized by DNA polymerase as indicated by the arrow, the end where new nucleotides are added is the 3' end, and the opposite end is the 5' end. Conversely, the bottom template strand runs in the opposite direction; the end aligned with the 3' end of the top strand is its 5' end, and the end aligned with the 5' end of the top strand is its 3' end.
The leading strand is synthesized continuously towards the replication fork, while the lagging strand is synthesized in short stretches called Okazaki fragments, which are later connected by the enzyme DNA ligase. The leading strand runs in the 5' to 3' direction towards the replication fork, and the lagging strand runs in the 5' to 3' direction away from the fork.