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.

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

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

a- all cells come from pre-existing cells