Skip to main content
Biology

Return to Question

Tweeted twitter.com/StackBiology/status/855953398033784835
edited tags
Link
Tyto alba
Tyto alba
  • 8.8k
  • 11
  • 70
  • 111
added 52 characters in body
Source Link
Tyto alba
Tyto alba
  • 8.8k
  • 11
  • 70
  • 111

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:54) ). 

I wonder why notthink removal of twist creates negative supercoils initially but when the unwinding causes too much overwinding of adjacent DNA, the strain developed cause the already negatively supercoiled DNA to form positive supercoils (alone?). If so at what point does removing twists no longer introduce negative supercoils but positive supercoils?

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:54) ). I wonder why not negative supercoils but positive supercoils (alone?). If so at what point does removing twists no longer introduce negative supercoils but positive supercoils?

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:54) ). 

I think removal of twist creates negative supercoils initially but when the unwinding causes too much overwinding of adjacent DNA, the strain developed cause the already negatively supercoiled DNA to form positive supercoils.

deleted 55 characters in body
Source Link
Tyto alba
Tyto alba
  • 8.8k
  • 11
  • 70
  • 111

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:541:54) ). I wonder why not negative supercoils but positive supercoils (alone?). If so at what point does removing twists no longer introduce negative supercoils but positive supercoils?

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:54) ). I wonder why not negative supercoils but positive supercoils (alone?). If so at what point does removing twists no longer introduce negative supercoils but positive supercoils?

When a twist is unwound without cutting the DNA strands or is removed by cutting the strand(s) and resealing, negative supercoils are introduced in the DNA.

enter image description here

From Cell and Molecular Biology -Karp

But strangely enough unwinding of DNA by helicase cause the DNA ahead of the primosome to form positive supercoils. Why is it so?

enter image description here

From: Molecular cell biology -Lodish

My speculations: Underwinding cause the adjacent DNA to overwind and as the DNA overwinds the associated stress developed cause the DNA to form positive supercoils (which would have happened naturally had new twists been introduced in the DNA (Time:1:54) ). I wonder why not negative supercoils but positive supercoils (alone?). If so at what point does removing twists no longer introduce negative supercoils but positive supercoils?

Source Link
Tyto alba
Tyto alba
  • 8.8k
  • 11
  • 70
  • 111