Which description correctly defines the lagging strand during DNA replication?

• A. Synthesized continuously toward the replication fork
• B. Synthesized using multiple primers in the opposite direction
• C. Synthesized in Okazaki fragments away from the fork
• D. Synthesized using a single primer

Answer: (C)

During DNA replication, the lagging strand is synthesized discontinuously as short segments called Okazaki fragments that extend away from the replication fork. This happens because DNA polymerase can only add nucleotides in the 5' to 3' direction, so on the lagging template (which runs 3' to 5' toward the fork) synthesis must occur in separate chunks moving away from the fork. Each fragment starts with an RNA primer laid down by primase, so multiple primers are required. After synthesis, the RNA primers are removed and replaced with DNA, and DNA ligase seals the gaps to make a continuous strand. This combination of fragmental synthesis and primer use is what defines the lagging strand.