Question

are the leading and lagging strands built differently during elongation?
a. an enzyme adds nucleotides to the lagging strand, but they
spontaneously attach to the leading strand.
b. the lagging strand is built in short segments, while the leading
strand is built continuously.
c. the lagging strand is built toward the replication fork, while the
leading strand is built away from the replication fork.
d. nucleotides are added to the 3 end of the leading strand and to
the 5 end of the lagging strand.

Explanation:

DNA replication occurs with the leading strand being synthesized continuously in the \(5'\) to \(3'\) direction towards the replication fork. The lagging strand, however, is synthesized discontinuously in short segments (Okazaki fragments) away from the replication fork. Nucleotides are added to the \(3'\) end of both strands (not \(5'\) for lagging as in option D). Enzymes are involved in adding nucleotides to both strands (so option A is wrong). Option C has incorrect direction - leading strand is built towards the replication fork.

Answer:

B. The lagging strand is built in short segments, while the leading strand is built continuously.