Question

What is the polarity of the template strand for the lagging strand?

Options

• Both 3′→5′ and 5′→3′

• 3′→5′

• No specific polarity requirement

• 5′→3′

Answer 1

The template strand for the lagging strand has a 5′→3′ polarity. This orientation necessitates discontinuous synthesis (away from the replication fork) because DNA polymerase can only synthesise in the 5′→3′ direction, which opposes the movement of the replication fork.