Question: What is the function of DNA topoisomerase?

Abstract DNA topoisomerases solve the topological problems associated with DNA replication, transcription, recombination, and chromatin remodeling by introducing temporary single- or double-strand breaks in the DNA.

What is the function of DNA topoisomerases quizlet?

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.

Why is topoisomerase important to DNA replication?

Topoisomerase also plays an important maintenance role during DNA replication. This enzyme prevents the DNA double helix ahead of the replication fork from getting too tightly wound as the DNA is opened up.

How does DNA topoisomerase work?

DNA topoisomerase-I works in the unwinding of double-stranded DNA. Here topoisomerase-I cuts one strand of DNA and allows another strand to pass through cut and rejoins the end. After completion of each topoisomerase-I activity, double-stranded DNA unwinds and linking the number of DNA is changed in a single step.

What is the function of DNA gyrase quizlet?

DNA gyrase (also referred to as topoisomerase) reduces supercoiling (relaxes tension) which builds up during DNA unwinding, preventing DNA breakage.

What is the function of Primase?

Primase functions by synthesizing short RNA sequences that are complementary to a single-stranded piece of DNA, which serves as its template. It is critical that primers are synthesized by primase before DNA replication can occur.

What are the functions of topoisomerase I and II?

Type I topoisomerases relax DNA (i.e., remove supercoils) by nicking and closing one strand of duplex DNA (see Figure 12-14). Type II topoisomerases change DNA topology by breaking and rejoining double-stranded DNA. Both replicated circular and linear DNA chromosomes are separated by type II topoisomerases.

What is the difference between DNA gyrase and topoisomerase?

DNA gyrase and topoisomerase IV are the two type II topoisomerases present in bacteria. Gyrase is involved primarily in supporting nascent chain elongation during replication of the chromosome, whereas topoisomerase IV separates the topologically linked daughter chromosomes during the terminal stage of DNA replication.

What is a primase simple definition?

Abstract. Primase is the enzyme that synthesizes RNA primers, oligonucleotides that are complementarily bound to a nucleic acid polymer. Primase is required because DNA polymerases cannot initiate polymer synthesis on single-stranded DNA templates; they can only elongate from the 3′-hydroxyl of a primer.

What happens if primase is not present?

Primase is required for the primer formation and to start the replication process by DNA polymerase. If primase is absent, DNA polymerase cannot initiate the process of replication because it can only add nucleotides to the growing chain.

What removes supercoiling?

The enzyme is thought to help maintain the proper superhelical density of the E. coli chromosome by removing negative supercoils formed by action of type II topoisomerase (DNA gyrase), which is discussed below.

Which one is known as DNA gyrase?

bacterial topoisomerase II DNA gyrase (also called bacterial topoisomerase II) is necessary for the supercoiling of chromosomal DNA in bacteria to have efficient cell division. Another related enzyme, topoisomerase IV, also is required for segregation of bacterial genomes into two daughter cells during cell division.

What is negative supercoiling of DNA?

Positive supercoiling of DNA occurs when the right-handed, double-helical conformation of DNA is twisted even tighter (twisted in a right-handed fashion) until the helix begins to distort and knot. Negative supercoiling, on the other hand, involves twisting against the helical conformation (twisting in a left-handed ...

What causes negative supercoiling?

Positive supercoiling of DNA occurs when the right-handed, double-helical conformation of DNA is twisted even tighter (twisted in a right-handed fashion) until the helix begins to distort and knot. Negative supercoiling, on the other hand, involves twisting against the helical conformation (twisting in a left-handed ...

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