Question

Question: A diploid nucleus of Drosophila melanogaster contains about 3.4 x 10⁸ nucleotide pairs. Assume (1) that all nuclear DNA is packaged in nucleosomes and (2) that an average internucleosome linker size is 60 nucleotide pairs. How many nucleosomes would be present in a diploid nucleus of D. melanogaster? How many molecules of histone H2a, H2b, H3, and H4 would be required?

ANS:   In the diploid nucleus of D. melanogaster, 1.65 x 10⁶ nucleosomes would be present; these would contain 3.3 x 10⁶ molecules of each histone, H2a, H2b, H3, and H4.

So I know this is the answer, but I am having a hard time understanding why and how to obtain this answer. Any help would be appreciated. This is for my genetics class by the way.

Answer 1

Let the number of nucleosomes in adiploid nucleus of D. melanogastern Then, the number of Patemucleosome Oures - x-1( Because hast nucleosome will not have this internucleosome linker) The number of nucleotide paiks in one nucleosome = 146 the number of nucleotide paires i u one iu temucleosome liuket = 60 Total number (Number of nuclearome Xprember of nucleotide' palus in one nucleolonel Number of Number 1 Xof nucleotide utenucleate = linker one internu classeme linker nucleotide pairs Sog X 146) + ((3-1) X60) = 34 x 108 146 x + 603-60, – 3.4 X108 17 +OS Ignore this because it is very small as compared to 3.4. X108 for substrating 206 n = 3. 4X108 x = 1.65 x 100 Nucleosomes. A each nucleosome contain a set of eight prokins called histone octamer. Coch octamer composed of t each of histone Proteins H2A, H2 B, H3 and 44. Number of molecules (total) = 2x Number of 2 Each histore nuclenomes I number = 2x1.65 x 106 3.3x10 molecules each.