# Basic biology and nanotechnology

• Nov 30th 2011, 02:00 PM
Logic
Basic biology and nanotechnology
I am not quite sure where this one is supposed to go, but I think there isn't any advanced math concepts in the solution of this problem, so I am posting it here...

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Chromosome packing is a key aspect of eukaryotic systems.
a) The first level of chromosome packing are nucleosomes. A single nucleosome core is 11 nm in diameter and contains 147 base pairs (bp) of DNA. The linker region of a nucleosome can contain up to 80 base pairs. The DNA double helix measures 0.34 nm/bp.

i. What packing ratio (the ratio of DNA length to nucleosome core diameter) has been achieved by wrapping DNA around the histone octamer?

ii. The packing ratio of the whole nucleosome is going to be lower than just the nucleosome core due to the linker region. Assuming the packing ratio of the whole nucleosome is 2.12, determine the number of nucleotides in the linker region.
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The first part is easy:
the ratio equals the number of base pairs times their size divided by the diameter of the sphere or 147*0.34 / 11 which is around 4.54.

But the second part seems quite elusive...
I think the base pairs that are not wrapped around a nucleosome core are not packed at all, so the packaging ratio is 1.
But I am all lost after that...
• Nov 30th 2011, 05:24 PM
mathland
Re: Basic biology and nanotechnology
This is not a math question. Place your interesting question is a biology forum.
• Dec 1st 2011, 02:10 AM
Logic
Re: Basic biology and nanotechnology
It is a math problem, with relevancy to reality.
To make it sound more math-like you can replace "nucleosome core" with "sphere" and "base pairs" with "circles".

When I said I was not sure where to place the problem, I was not wondering what site to post it to, only where here to post it to, because I am not quite sure under what math category this falls. But it definitely is mathematics...