Which of the following will be observed in a bacterium that lost its ability to make DNA gyrase. You will find many small fragments of DNA in the cytoplasm of the bacterium The bacterium will be unable to replicate its DNA Nothing bad since DNA gyrase is not important in the life a bacterium The Bacterium will struggle to initiate DNA replication
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Step 1: Define DNA gyrase — it is a bacterial type II topoisomerase that relieves positive supercoiling ahead of replication forks and can introduce negative supercoils. Show more…
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A deletion occurs in a gene that encodes DNA polymerase in E. coli, and no functional DNA polymerase is produced. What will be the most likely consequence of this mutation? The DNA would not exist in a supercoiled state. The DNA strands would contain pieces of RNA. The DNA will not be able to unwind to initiate replication. There would be no DNA replication on the leading or lagging strands. Nothing; everything will continue as normal.
Bryan V.
How would the replication be affected in a cell? If there were DNA gyrase (also known as topoisomerase) present, the replication would proceed faster than usual, creating more mistakes and an overall reduction in fidelity. Torsional strain ahead of the replication fork would cause the DNA helicase to eventually cause replication to no longer synthesize the DNA linear strands. Replication could only occur on the leading strand. The newly synthesized chromosomes would recombine higher. Question 42 What is the function of DNA ligase? Ligase connects Okazaki fragments by sealing nicks. Ligase reduces the torsional strain that builds up ahead of the replication fork as a result of unwinding. Ligase prevents the formation of secondary structure.
A mutant strain of E. coli has been identified that has both a gain of function mutation of helicase that doubles its activity and a loss of function mutation in DNA gyrase that reduces its affinity for DNA. Explain the impact, if any, on the rate of DNA replication in this bacterial strain.
Jenny W.
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