What is chromatin vs nucleosome?

Here's a breakdown of chromatin vs. nucleosomes:

• Nucleosome: A nucleosome is the fundamental repeating unit of <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>. It's essentially the first level of DNA organization in eukaryotes. A nucleosome consists of a core of eight histone proteins (two each of H2A, H2B, H3, and H4) around which approximately 146 base pairs of DNA are wrapped. The DNA is held in place by the histone fold domain.

• Chromatin: <a href="https://www.wikiwhat.page/kavramlar/chromatin">Chromatin</a> refers to the complex of DNA and proteins (mainly histones) that make up chromosomes within the nucleus of eukaryotic cells. It is the substance of heredity. Think of chromatin as the "packaged" form of DNA. It exists in two main forms:

  • Euchromatin: Loosely packed <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>; transcriptionally active.
  • Heterochromatin: Densely packed <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>; transcriptionally inactive.

• Relationship: Nucleosomes are the building blocks of <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>. Imagine nucleosomes as beads on a string; the "string" is the DNA, and the arrangement and modification of these "beads" (nucleosomes) influence the overall structure and function of the "string" (<a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>).

• Function:

  • Nucleosomes: Primary role is DNA packaging. They compact the DNA, making it fit into the nucleus. They also play a role in regulating gene expression.
  • Chromatin: Its function is to efficiently package DNA to fit into the nucleus, protect the DNA structure, and regulate gene expression and DNA replication. The structure of <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a> can change to allow or restrict access to genes.

In essence, nucleosomes are a component of <a href="https://www.wikiwhat.page/kavramlar/chromatin">chromatin</a>.