Question

Expression of a particular mutation in E. coli causes half of newly synthesized DNA to persist as fairly short fragments. The mutation most likely affects a gene that encodes DNA

A. ligase.
B. polymerase.
C. exonuclease.
D. gyrase.
E. single-stranded binding proteins.

Answer 1

The mutation likely affects DNA ligase, which is essential for joining short DNA fragments (Okazaki fragments) on the lagging strand during DNA replication in E. coli.

Step-by-step explanation:

The question addresses a scenario where a mutation in E. coli causes newly synthesized DNA to persist as short fragments, suggesting a deficiency in the DNA replication process. The correct answer to which gene product is most likely affected by this mutation is DNA ligase. DNA ligase is crucial for connecting Okazaki fragments on the lagging strand during DNA replication. Without a properly functioning DNA ligase, the E. coli will have difficulty joining the short DNA fragments synthesized on the lagging strand, resulting in the persistence of these fragments. This is supported by studies such as those by Reiji Okazaki and colleagues on T4 phage.