Question

which of the following statements correctly describes how the leading and the lagging strands of dna formed during dna replication differ?
the leading strand is synthesized at twice the rate of the lagging strand.
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together.
the leading strand is synthesized by adding nucleotides to the 3 end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5 end.

Explanation:

• Option 1: There is no general rule that the leading strand is synthesized at twice the rate of the lagging strand. The rate can be influenced by many factors and is not a fundamental difference in their synthesis mechanisms.
• Option 2: During DNA replication, the leading strand is synthesized continuously in the \(5'\to3'\) direction in the same direction as the movement of the replication fork. The lagging strand is synthesized discontinuously in the \(5'\to3'\) direction but in the opposite direction relative to the movement of the replication fork (as Okazaki fragments).
• Option 3: It is the leading strand that is synthesized continuously, and the lagging strand is synthesized in short Okazaki fragments that are later joined together.
• Option 4: Both the leading and the lagging strands are synthesized by adding nucleotides to the \(3'\) end of the growing strand. DNA polymerase (the main enzyme for DNA synthesis) works only in the \(5'\to3'\) direction for both strands.

Answer:

The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.