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Questions tagged [supercoiling]

Supercoiling is a form of DNA in which the double helix is further twisted about itself, forming a tightly coiled structure.

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DNA Topology of two circular chromosomes

I'm reading DNA Topology: Fundamentals from where I quote : Topological aspects of DNA structure arise primarily from the fact that the two DNA strands are repeatedly intertwined. Untangling these ...
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DNA topology Linking number vs twist?

Background Linking number: the linking number represents the number of times that each curve winds around the other. Twist, called "twist", refers to the number of Watson-Crick twists in the ...
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Reason behind formation of positive supercoils during DNA replication/ transcription

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. From Cell and Molecular Biology -Karp But ...
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Why is compensatory negative supercoiling generated in a positively supercoiling ccDNA?

I was reading DNA replication in E.coli in Lehninger Principles of Biochemistry 6th Ed. and stumbled upon the following -- The tight right handed wrapping of DNA around DnaA oligomeric complex ...
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Why does underwinding create topological strain of DNA?

I am currently studying the supercoiling of DNA. I understand why overwinding would create additional strain for two attached strands of DNA, but I really don't get why underwinding would create ...
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Topological property of DNA

I was reading a course about DNA Supercoiling, and I stopped at this definition : [...] In the case of DNA, a topological property is one that is not affected by twisting and turning of the DNA ...
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Over winding vs under winding of a DNA

DNA supercoiling refers to the over- or under-winding of a DNA strand. Source : DNA supercoil When a relaxed DNA is subjected to bends, or openings of DNA, over winding or unwinding, its base ...
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What is a topological domain?

I found this definition on Wikipedia, but I didn't quit undestand it : Topologically associating domains (TADs) are genomic regions ("chromosome neighborhoods") used to summarize the three-...
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Does DNA helicase or topoisomerase actually “unwind” DNA?

I am reading through my textbook (Genetics, Brooker 4th edition) and the summary it gives seems imprecise for the functionality of helicase and topoisomerase. The following is an exerpt: ...
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What is positive and negative supercoiling?

Is the following correct? Positive supercoiling = the coiling of DNA helix (B-DNA) on itself during intesified coiling of the two DNA stands in right handed direction negative supercoiling = the ...
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Why does supercoiled DNA run faster?

The DNA exists in linear and cirular forms. The latter form has interesting feature called Supercoiling. The more number of writhe makes it more supercoiled because of which it gets more compact. ...
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Why do most organisms have negative supercoiled DNA?

It has been observed that in nature most organisms have negative supercoiled DNA and that few organisms have positive supercoiled DNA. Some of the organisms that have the positive supercoiled DNA live ...
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Nucleosome wrapping direction

Does anyone know which direction the nucleosomes are wrapped? I wonder: Relative to the B-DNA double helix twist direction (right-hand) Relative to the neighbor nucleosomes. Do they alternate to ...
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Understanding DNA supercoiling

While trying to understand DNA supercoiling, I came across these lines in the book Genetics by Ursula Goodenough : All natural DNA is superhelical. The axis of the duplex itself follows a helical ...
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Improving transformation efficiencies- induce supercoiling?

From my limited knowledge of science, I know transformation can be one of the hardest step in cloning, and that a large amount of research/trial and error has been done to improve on this step. I've ...