what would happen if, in the course of replication, the topoisomerases were unable to reattach

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What happens to telomeres without functional telomerase?

Where are DNA polymerases positioned?

Does DNA depend on replication?

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What would happen if topoisomerase is not available for DNA replication?

Topoisomerase alleviates supercoiling downstream of the origin of replication. In the absence of topoisomerase, supercoiling tension would increase to the point where DNA could fragment. DNA replication could not be initiated because there would be no RNA primer. DNA strands would not be ligated together.

What happens if topoisomerase stops working?

Topoisomerases are enzymes that are abundantly present in our cells and can temporarily cut and rejoin our DNA to remove knots and tangles that form during important biological processes. If they fail to do their job, cells may die.

Is topoisomerase required for DNA replication?

DNA replication requires other enzymes in addition to DNA polymerase, including DNA primase, DNA helicase, DNA ligase, and topoisomerase.

Why is topoisomerase needed?

Topoisomerases are nuclear enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of topoisomerases: type I, which makes single-stranded cuts in DNA, and type II enzymes, which cut and pass double-stranded DNA.

What is the role of topoisomerase during DNA replication quizlet?

What is the function of the enzyme topoisomerase in DNA replication? relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix (Topoisomerases are enzymes that participate in the over winding or underwinding of DNA.

What is topoisomerase in DNA replication?

DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA.

Where would the enzyme topoisomerase attach during DNA replication?

Answer and Explanation: The enzyme topoisomerase attaches to DNA in front of the replication fork.

Why is the Phosphotyrosine formation in the active site of DNA topoisomerases crucial for the functioning of DNA topoisomerases?

phosphorus of the phosphotyrosine link, breaking the covalent bond between the protein and DNA, and re- forming the DNA backbone bond. These reactions cre- ate transient enzyme-mediated gates in the DNA for the passage of another DNA strand or double helix.

What would happen if DNA ligase stopped working?

If the enzymatic molecule of DNA ligase is mutated and it becomes non-functional, the single strands of the replicated as well the newly synthesized DNA would not be joint, and by the end of the replication mechanism, DNA fragments will be present instead of proper DNA structure.

What is the function of topoisomerase 2 in DNA replication?

Topoisomerase IIα is found at replication forks and remains tightly associated with chromosomes during mitosis [13,39]. Thus, topoisomerase IIα is believed to be the isoform that functions in growth-dependent processes, such as DNA replication and chromosome segregation [7,13].

What is the role of topoisomerases in eukaryotic DNA replication Mcq?

i) Topoisomerase II- converts a positive supercoil to a negative supercoil, also known as gyrase. ii) Polymerase I- larger (Klenow) fragment is responsible for polymerase activity. iii) DnaB protein- also known as helicase helps in unwinding of DNA duplex to form the open complex.

What is the function of topoisomerase in the eukaryotic cell?

Topoisomerase II is a ubiquitous enzyme that is essential for the survival of all eukaryotic organisms and plays critical roles in virtually every aspect of DNA metabolism. The enzyme unknots and untangles DNA by passing an intact helix through a transient double-stranded break that it generates in a separate helix.

How does topoisomerase affect DNA replication?

DNA topoisomerases unravel twists in DNA that occur as a result of DNA transcription and replication. The DNA topoisomerases I and II present in cells act through scission of the DNA backbone on one or two strands, respectively, followed by relief of torsional stress and then relegation of the broken DNA backbone.

What would happen if DNA ligase stopped working?

If the enzymatic molecule of DNA ligase is mutated and it becomes non-functional, the single strands of the replicated as well the newly synthesized DNA would not be joint, and by the end of the replication mechanism, DNA fragments will be present instead of proper DNA structure.

Does topoisomerase unwind DNA?

DNA topoisomerases are ubiquitous enzymes found in all cell types from viruses to man. These enzymes act to regulate DNA supercoiling by catalysing the winding and unwinding of DNA strands.

Does topoisomerase break covalent bonds?

Topoisomerase breaks a covalent bond in the backbone of one parental strand. ( Topoisomerase relieves the strain caused by unwinding of the DNA by helicase. First, it binds to the parental DNA ahead of the replication fork.

What happens to telomeres without functional telomerase?

Without functional telomerase, the telomeres would shorten at each replication cycle, leading to eventual loss of essential coding information and death. Some current observations indicate that decline or loss of telomerase activity plays a role in the mechanism of aging in humans.

Where are DNA polymerases positioned?

26.) The DNA polymerases are positioned over the following DNA segment (which is part of a much larger molecule) and moving from right to left. If we assume that an Okazaki fragment is made from this segment, what will be the fragment's sequence?

Does DNA depend on replication?

No. The information of DNA depends on a faithful copying mechanism. The strict rules of complemetarity ensure that replication and transcription are reproducible.

What happens to telomeres without functional telomerase?

Without functional telomerase, the telomeres would shorten at each replication cycle, leading to eventual loss of essential coding information and death. Some current observations indicate that decline or loss of telomerase activity plays a role in the mechanism of aging in humans.

Where are DNA polymerases positioned?

26.) The DNA polymerases are positioned over the following DNA segment (which is part of a much larger molecule) and moving from right to left. If we assume that an Okazaki fragment is made from this segment, what will be the fragment's sequence?

Does DNA depend on replication?

No. The information of DNA depends on a faithful copying mechanism. The strict rules of complemetarity ensure that replication and transcription are reproducible.