Question

The plant species Arabidopsis thaliana has a genome containing approximately 135 million bp of DNA. For this problem, assume Arabidopsis has a core-DNA length of 145 bp and a linker-DNA length of 55 bp.

Determine the approximate number of nucleosome in each nucleus. Determine approximately how many molecules of histone protein H4 are found in each nucleus.

Answer 1

700,000 nucleosomes and 1,400,000 H4 proteins

Step-by-step explanation:

Number of base pairs for each nucleosome: 145 bp (core-DNA length) + 55 bp (linker-DNA length) = 200 bp

Genome size = 135 million bp of DNA = 135,000,000 bp >>

>> Number of nucleosomes in each nucleus = 135,000,000 / 200 = 700,000 nucleosomes

A nucleosome is composed of two copies of the H2A, H2B, H3, and H4 core histone proteins. In consequence, a nucleosome contains 2 two copies of the H4 histone protein >>

>> Number of H4 in each nucleus = 700,000 nucleosomes x 2 = 1,400,000 H4 proteins