THE MOLECULAR BASIS OF INHERITANCE
DNA REPLICATION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
topoisomerase
|
|
|
helicase
|
|
|
polymerase
|
|
|
ligase
|
Detailed explanation-1: -Helicase unwinds the helix, and single-strand binding proteins prevent the helix from re-forming. Topoisomerase prevents the DNA from getting too tightly coiled ahead of the replication fork.
Detailed explanation-2: -Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
Detailed explanation-3: -Topoisomerase I is proposed to work ahead of the replication fork to remove positive DNA supercoils, whereas topoisomerase II is proposed to work primarily behind the fork to remove precatenanes.
Detailed explanation-4: -Of all the enzymes required to sustain cellular growth, topoisomerase II is one of the most dangerous (4–8). As discussed below, this enzyme unwinds, unknots and untangles the genetic material by generating transient double-stranded breaks in DNA (8–12).
Detailed explanation-5: -Topoisomerase is responsible for initiation of the unwinding of the DNA. The tension holding the helix in its coiled and supercoiled structure can be broken by nicking a single strand of DNA.