Question

You have a bacterial cell in which a mutation occurred. You observe that Okazaki fragments are created but RNA primers are not removed. Which gene is mutated?

a) DNA helicase
b) DNA ligase
c) DNA primase
d) RNase H

Answer 1

The most likely mutated gene responsible for the failure to remove RNA primers in bacterial cell DNA replication, despite the creation of Okazaki fragments, is that coding for RNase H.

Step-by-step explanation:

When you observe that RNA primers are not being removed during DNA replication in a bacterial cell, but Okazaki fragments are being created, it indicates an issue with the processing of these fragments on the lagging strand. During DNA replication, RNA primers must be removed and replaced with DNA nucleotides before the fragments are joined together. The enzyme which normally has this function is DNA polymerase I, which removes the RNA primer and fills in the gap with DNA nucleotides. Then DNA ligase seals these nicks, joining the Okazaki fragments into a continuous DNA strand.

Since you observe that Okazaki fragments are present but RNA primers are not removed, the most likely mutated gene is that coding for RNAse H, which is an enzyme that removes RNA primers during DNA replication. DNA polymerase I then fills in the spaces previously occupied by RNA. If the RNA primers are left in place, DNA ligase cannot join the Okazaki fragments, resulting in an incomplete replication process.