Question

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation

Answer 1

Answer:

The question lacks options, the options are:

A) No proofreading will occur. B)The DNA will supercoil. C)Replication will occur via RNA polymerase alone.

D)No replication fork will be formed.

E)Replication will require a DNA template from another source.

The answer is D

Explanation:

Prior to division of any cell, its genetic material needs to be replicated. Ideally, in a bacterial cell, this replication starts at a particular nucleotide sequence called ORIGIN OF REPLICATION. An enzyme called DNA HELICASE then binds to the origin of replication and breaks the hydrogen bonds between the double-stranded DNA molecule to form a Y-shaped Replication fork, which serves as a template for DNA polymerase III to bind and begin to add nucleotides.

However, if a mutation occurs at a certain gene dNAb and alters the action of HELICASE enzyme. Thus, it prevents the helicase from separating the double-strands of the DNA molecule containing the gene. Hence, no replication fork will be formed and subsequently no template for DNA polymerase's action.