Along a 18000-bp segment of dna, approximately how many molecules of each kind of histone protein do you expect to find?

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Biology

Isabell Todd

2 July, 04:30

Along a 18000-bp segment of dna, approximately how many molecules of each kind of histone protein do you expect to find?

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Belinda · Answer 1

Nucleosomes are structured as follows: Two each of the histones H2A, H2B, H3, and H4 come together to form a histone octamer, which binds and wraps about 1.7 turns of DNA, or about 147 base pairs. The addition of one H1 protein wraps another 20 base pairs, resulting in two full turns around the octamer. These nucleosomes are joined by the DNA that runs between them (an average of about 40 base pairs). This joining DNA is referred to as linker DNA.

So, a total of 197 base pairs are used up in one nucleosome.

So, total no. of H1 = 6000/197 = 30

Total total no. each of H2A, H2B, H3, H4 = 2 * no. of H1

= 2*30 = 60 each.