Question

Chromatin of eukaryotes is organized into repeating interactions with protein octamers called nucleosomes. Nucleosomes are composed of which class of molecules?

a. histones
b. glycoproteins
c. lipids
d. nonhistone chromosomal proteins

Answer 1

Nucleosomes are composed of histones, which are proteins that organize eukaryotic chromatin by forming an octamer that DNA wraps tightly around, leading to the 'beads on a string' structure.

Step-by-step explanation:

Nucleosomes are composed of a class of molecules known as histones. Histones are evolutionarily conserved proteins that are rich in basic amino acids. They form an octamer around which DNA is tightly wrapped, representing a key organizational component of eukaryotic chromatin. A nucleosome is related to the next one by linker DNA, which leads to the so-called "beads on a string" structure. This structure then compacts further into a 30 nm fiber during the chromatin condensation process. During cell division, specifically at the metaphase stage, chromatin is at its most compact form, reaching approximately 700 nm in width and associating with scaffold proteins to further structure chromosomes.