Question

When the initiation site is removed from the β-globin gene cluster, how is that section of the chromosome replicated?

a. It is not replicated.
b. A new replication initiation site is transposed to the original site of the excised replication initiation site.
c. This part of the chromosome is replicated by a replication fork that moves into the region from an unidentified origin outside the β-globin cluster.
d. A mutation creates a new replication initiation site near this region of the chromosome.

Answer 1

When the initiation site is removed from the β-globin gene cluster, the section of the chromosome is replicated by a replication fork that moves into the region from an unidentified origin outside the β-globin cluster.

Step-by-step explanation:

When the initiation site is removed from the β-globin gene cluster, the section of the chromosome is replicated by a replication fork that moves into the region from an unidentified origin outside the β-globin cluster. The replication fork is formed when the enzyme helicase separates the DNA strands by breaking the hydrogen bonds between the base pairs. This allows for bidirectional replication and the formation of a replication bubble.

The events taking place at the replication fork are crucial for the accurate duplication of DNA. Helicase is one such enzyme that unwinds the DNA helix, allowing replication to occur. If the gene for helicase is mutated, the unwinding portion of replication will be affected, potentially preventing the replication machinery from accessing the DNA template. As a result, DNA replication could be significantly slowed or stopped.