Concept explainers
Figure 9.10 You isolate a cell strain in which the joining together of Okazaki fragments is impaired and suspect that a mutation has occurred in an enzyme found at the replication fork. Which enzyme is most likely to be mutated?
To write:
The enzyme which is most likely mutated when joining of Okazaki fragments is impaired in the replication.
Introduction:
DNA replication is the process in which the copy of DNA is made. This is done in 3 steps in a eukaryotic cell. They are initiation, elongation, and termination. It is a semiconservative type of replication. Enzymes involved in this process are helicase, DNA polymerase, and DNA ligase.
Explanation of Solution
DNA replication is started at the origin of replication where a Y shaped fork known as replication is formed when both strands are separated by helicase enzyme. Both the strands of DNA act as a template. One strand is known as a leading strand at which replication is continuous and other strand is known as a lagging strand at which replication occurs in fragments. This is because DNA polymerase can synthesize DNA only in 5' to 3' direction. These fragments are known as Okazaki fragments. These fragments at the lagging strands are then sealed by the enzyme DNA ligase. The joining of Okazaki fragments is impaired when the DNA ligase is not able to join the strands. This can occur due to the mutation in enzyme DNA ligase.
When joining of DNA fragments on the lagging strand is impaired in DNA replication, the mutation is most likely to occur in DNA ligase as it is an important enzyme which joins the strands.
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