Table of Contents
- 1 Which enzyme is involved in relaxation of supercoiled DNA?
- 2 Which of the following enzymes would relax negatively supercoiled DNA?
- 3 Which enzyme introduces negative supercoiling in DNA?
- 4 What increases positive supercoiling in DNA?
- 5 Which enzyme increases positive supercoiling in DNA?
- 6 What enzyme causes positive supercoiling?
- 7 What is the purpose of DNA supercoiling?
- 8 What causes supercoiling of DNA?
Which enzyme is involved in relaxation of supercoiled DNA?
Type I Topoisomerases
Type I Topoisomerases These enzymes are primarily responsible for relaxing positively and/or negatively supercoiled DNA. TopIA enzymes transiently cleave a single strand of supercoiled DNA to form a 5′- phosphotyrosyl intermediate.
Which of the following enzymes would relax negatively supercoiled DNA?
topoisomerases
DNA gyrase is unique among all topoisomerases and is the only enzyme that is able to negatively supercoil the double helix.
Which enzyme introduces negative supercoiling in DNA?
DNA gyrase is the only type II topoisomerase able to introduce negative supercoils into DNA, a feature that requires the enzyme to dictate the directionality of strand passage.
Which of the following is responsible for the conversion of covalently closed circular DNA to supercoiled DNA of plasmid?
Q13: Which of the following is responsible for the conversion of covalently closed circular DNA to supercoiled DNA of the plasmid? Explanation: If both strands of DNA are intact, it is in a relaxed form called CCC DNA, if only one strand is intact it is called open circular DNA.
What is the difference between topoisomerase I and II?
Topoisomerase I and II are methods of dealing with supercoiled DNA. Topoisomerase I cuts one strand in the double-stranded DNA and no ATP is required for its function. On the other hand Topoisomerase, II cuts both strands in DNA and needs ATP for its activity. This is the key difference between Topoisomerase I and II.
What increases positive supercoiling in DNA?
Unwinding of the helix during DNA replication (by the action of helicase) results in supercoiling of the DNA ahead of the replication fork. This supercoiling increases with the progression of the replication fork.
Which enzyme increases positive supercoiling in DNA?
Among the proteins involved in DNA replication are several that change the topology of DNA: helicases, which can unwind the DNA duplex, thereby inducing formation of supercoils, and topoisomerases, which catalyze addition or removal of supercoils.
What enzyme causes positive supercoiling?
Topology of DNA can be disrupted by most metabolic processes: RNA polymerase can cause positive supercoils by over-winding the DNA in front of the enzyme, and can also cause negative supercoils by under-winding the DNA behind the enzyme.
What is the difference between topoisomerase 1 and 2?
What is the function of topoisomerase II?
EC no. Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change the linking number of circular DNA by ±2.
What is the purpose of DNA supercoiling?
DNA supercoiling is important for DNA packaging within all cells. Because the length of DNA can be thousands of times that of a cell, packaging this genetic material into the cell or nucleus (in eukaryotes) is a difficult feat. Supercoiling of DNA reduces the space and allows for DNA to be packaged.
What causes supercoiling of DNA?
Supercoiling occurs when the molecule relieves the helical stress by twisting around itself. The hydrogen bonds (holding together complementary bases) break and part of the double helix separates. Strand separation is required for transcription (copying DNA to RNA) and replication (copying DNA to DNA).