DNA unwinding, such as that occurring in replication, affects the superhelical d

Question

DNA unwinding, such as that occurring in replication, affects the superhelical density of DNA. In the absence of topoisomerases, the DNA would become over wound ahead of a replication fork as the DNA is unwound behind it. A bacterial replication fork will stall when the superhelical density (sigma) of the DNA ahead of the fork reaches sigma = 0.14. Bidirectional replication is initiated at the origin of a 6,000 bp plasmid in vitro, in the absence of topoisomerases. The plasmid initially has a sigma of 0.06. How many base pairs will be unwound and replicated by each replication fork before the forks stall? Assume that each fork travels at the same rate and that each includes all components necessary for elongation except topoisomerase

Explanation / Answer

Super helical activity of DNA is seen in replication during absence of topoisomerase will cause DNA to become more and more wounded and it is by positive sigma which denotes the percent of DNA supercolied and wound and the same negative sigma denotes the percent of DNA remained to be unwounded in presence of isomerase here in this experiment we cans see the DAN unwinding has stopped 600 base pairs ahead of sigma value 0.14 that means 1.4% of DNA is still needs to be unwounded and in other case with sigma value of 0.06 means around 0.6% of DNA needs to be unwounded and it is over wounded and it is ahead of around 2500 base pairs of DNA.

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.