How does circular DNA wrap around a histone to form a chromosome?

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Circular DNA does not wrap around histones to form chromosomes; instead, it is compacted with the assistance of various proteins, such as HU, particularly in prokaryotes and organelles like mitochondria. Histones, which are positively charged proteins, interact with negatively charged DNA through electrostatic attraction, facilitating the organization of linear DNA into chromatin structures in eukaryotes. The regulation of DNA wrapping is influenced by transcription machinery, which is essential for managing the extensive length of DNA, such as the 2.2 meters found in humans. This organization leads to the formation of euchromatin and heterochromatin, observable through electrophoresis and DNA banding patterns.
gauss44
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How does circular DNA wrap around a histone to form a chromosome? Or does it?

I am having a hard time visualizing this for any sort of circular DNA: prokaryotes, mitochondria, etc.

(This question was inspired by my reading about biology and reading that circular DNA does, in fact, form chromosomes. So, now I'm wondering how?)
 
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come on, guys …

somebody must know the answer to this! :smile:
 
tiny-tim said:
come on, guys …

somebody must know the answer to this! :smile:

I'm not a biologist, but this set of images from missouri.edu seems to explain it. I have no reason to think it's inaccurate.

http://web.missouri.edu/~vandorens/Biochem8240/lectures/Nucl_acid_supercoil_1oct12.pdf
 
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gauss44 said:
How does circular DNA wrap around a histone to form a chromosome?

Histone are proteins made up of amino acids (basic) ex. lysine and arginine , that are positively charged.on the other hand DNA contains phosphorus backbone(PO4 3-). so this is an electrostatic attraction and nothing else.
also, some transcription regulatory machinery regulates this wrapping otherwise the length of DNA is 2.2m in Humans.
Due to this euchromatin and Heterochromatin is seen under Electrophoresis and DNA banding patterns.
 
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