Final answer:
DNA replication is efficient on the leading strand because DNA polymerase reads the strand in the correct orientation, allowing for continuous nucleotide addition and a built-in proofreading mechanism to correct errors.
Step-by-step explanation:
The leading strand proceeds without difficulty during DNA replication because DNA polymerase can read it. In this context, DNA polymerase moves along the template strand, which is in the 3' to 5' direction, and it adds nucleotides to the new complementary leading strand in the 5' to 3' direction. This synthesis of the leading strand is continuous because it is oriented in such a way that the polymerase can add nucleotides toward the replication fork seamlessly.
Furthermore, DNA polymerase also has a proofreading function where it reads the newly added base before adding the subsequent one to ensure accuracy. If a mismatch is detected, DNA polymerase uses its 3' exonuclease activity to remove the incorrect nucleotide and then replaces it with the correct one. This proofreading ability helps keep the replication process accurate and minimizes the occurrence of errors.
While the replication of the leading strand is straightforward, the lagging strand, on the other hand, requires a bit more complex process called Okazaki fragments which are synthesized discontinuously.