BIOMOLECULES AND ENZYMES

Detailed explanation-1: -All known DNA polymerases share two fundamental properties that carry critical implications for DNA replication (Figure 5.2). First, all polymerases synthesize DNA only in the 5′ to 3′ direction, adding a dNTP to the 3′ hydroxyl group of a growing chain.

Detailed explanation-2: -One new strand, which runs 5’ to 3’ towards the replication fork, is the easy one. This strand is made continuously, because the DNA polymerase is moving in the same direction as the replication fork. This continuously synthesized strand is called the leading strand.

Detailed explanation-3: -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. The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together.

Detailed explanation-4: -The helicase unzips the double-stranded DNA for replication, making a forked structure. The primase generates short strands of RNA that bind to the single-stranded DNA to initiate DNA synthesis by the DNA polymerase. This enzyme can work only in the 5’ to 3’ direction, so it replicates the leading strand continuously.