You are studying DNA replication in bacteria. You find a cell that you know is a

Question

You are studying DNA replication in bacteria. You find a cell that you know is a knockout of ONE of the DNA replication enzymes. When this cell replicates its DNA you get a few large fragments of new DNA and a whole bunch of smaller Okazaki fragments, but the final DNA strand is never formed. There are 2 enzymes that might be missing, what are they? Design an experiment which would tell you which of these enzymes is missing in your case. You can’t look for the proteins themselves, you can only look at the DNA that is being produced

Explanation / Answer

During DNA replication, a leading strand and a lagging strand are amplified. The lagging strand is amplified in small fragments which are called Okazaki fragments. These fragments are sealed to form a complete DNA strand. Just after this sealing, two enzymes play critical functions. Enzyme topoisomerase II performs the removal of positive supercoils from the DNA ahead of the replication site so that further the supercoils might be reduced and replication might proceed smoothly.. Secondarily, the enzyme DNA polymerase I removes the primers from the Okazaki fragment whose replication is delayed.

According to the information, the DNA strand is amplified in small strands but does not complete. It is very likely that these two enzymes i.e. topoisomerase II and DNA polymerase I are missing from this system leading to this impairment.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.