Chapter 11, Problem 18P

Summary Introduction

To analyze:

Considering that in Arabidopsis thaliana, the approximate number of nucleosomes per nucleus is $5\times {10}^5$ in $\text{G1}$ phase of the cell cycle, answer the following questions:

How many nucleosomes are expected in the nucleus after completion of S phase? Explain.

Are all of the additional nucleosomes that are present after completion of S phase of the cell cycle composed of newly synthesized histone proteins? Explain.

Introduction:

During the S phase of the cell cycle, the DNA content of the cell is doubled by the replication of DNA. This replication results in each chromosome containing two identical sister chromatids. The newly synthesized DNA is organized by nucleosome core particles. The nucleosome is wrapped by core DNA and the spans between nucleosomes consist of linker DNA.