Question

When the DNA is replicated, the DNA double helix is unwound to form the replication bubble. Explain the process and enzymes when the DNA bubble is formed

Answer 1

The formation of the replication bubble occurs in several steps and involves several enzymes:

1. Initiation: The DNA helicase (enzyme) binds to the origin of replication site and begins to unwind the double-stranded DNA.

2. Formation of the replication bubble: As the helicase moves along the DNA, it creates a replication bubble where the DNA strands are separated. DNA polymerase (enzyme) attaches to each of the separated strands and begins to add complementary nucleotides to form new strands.

3. Elongation: DNA polymerase adds nucleotides continuously to the leading strand, which runs in the 5’ to 3’ direction. It adds nucleotides in a discontinuous manner to the lagging strand, which runs in the opposite direction, in small sections known as Okazaki fragments.

4. Joining of fragments: The Okazaki fragments are eventually joined together by DNA ligase (enzyme), which seals any gaps between the fragments and creates a continuous strand.

Overall, the formation of the replication bubble allows for the efficient replication of DNA, with multiple replication bubbles forming along the DNA molecule to speed up the process.