THE MOLECULAR BASIS OF INHERITANCE
DNA REPLICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Gyrase which creates tension in the double helix.
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Gyrase which relieves tension in the double helix.
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Helicase which creates tension in the double helix.
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Helicase which relieves tension from the double helix.
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Detailed explanation-1: -DNA gyrase, is the type II topoisomerase enzyme that is primarily involved in relieving positive supercoiling tension that results due to the helicase unwinding at the replication fork.
Detailed explanation-2: -The first step in DNA replication is to ‘unzip’ the double helix structure of the DNA? molecule. This is carried out by an enzyme? called helicase which breaks the hydrogen bonds? holding the complementary? bases? of DNA together (A with T, C with G).
Detailed explanation-3: -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.
Detailed explanation-4: -The untwisting of the double helix by helicase causes additional twisting of the DNA molecule ahead of the replication fork. Topoisomerase is the enzyme that helps to relieve this strain by breaking, untwisting and rejoining the DNA strands.
Detailed explanation-5: -DNA gyrase controls replication initiation by inhibiting DnaA binding and activity at the origin of replication, oriC. Inhibition of gyrase increases replication initiation frequency and DnaA association with oriC, and is harmful to cell survival if replication initiates from oriC.