Study guide
Nucleosomes study guide
The nucleosome is the basic repeating packaging unit of eukaryotic chromatin: DNA wrapped around a histone octamer. This hub connects structure language to packaging explorers and chromatin topics.
What you will learn
- Octamer composition and wrapped DNA
- Linker DNA and H1 in higher-order packaging discussions
- Nucleosome positioning as an accessibility concept
- Practice with the nucleosome explorer
Core lessons
Start with the primary article, then branch into closely related concepts.
- Nucleosome — The nucleosome is the basic repeating unit of chromatin: DNA wrapped around a histone octamer.
- Nucleosome structure — Nucleosome structure details the histone octamer, wrapped DNA, and protruding histone tails.
- Nucleosome positioning — Nucleosome positioning refers to where nucleosomes sit along DNA and how that placement affects access to sequences.
- Histones — Histones are the core packaging proteins of chromatin that form the nucleosome octamer.
- Linker DNA — Linker DNA is the DNA segment connecting adjacent nucleosomes in a chromatin array.
- Chromatin — Chromatin is the DNA–protein complex that packages eukaryotic genomes and helps regulate gene access.
- DNA packaging — DNA packaging describes how long DNA molecules are folded with proteins to fit and function in cells.
Comparisons
- Chromatin vs DNA — DNA is the genetic polymer; chromatin is DNA packaged with proteins in eukaryotic nuclei.
Interactive practice
Explorers
- Nucleosome structure explorer — Explore the histone octamer (H2A, H2B, H3, H4), wrapped DNA, linker DNA, and H1 in context.
- DNA packaging explorer — Interactive zoom from DNA through histones, nucleosomes, chromatin, and condensed chromosomes.
Tools
Worksheets
- Chromatin worksheets — Chromatin vocabulary, packaging labels, and euchromatin vs heterochromatin contrasts.
Glossary terms
- Nucleosome — The nucleosome is the basic repeating unit of chromatin: DNA wrapped around a histone octamer.
Common questions
What is a nucleosome?
A nucleosome is a complex in which DNA wraps around a histone octamer (two each of H2A, H2B, H3, and H4). Nucleosomes repeat along DNA and are the building blocks of chromatin.
How does DNA packaging start?
Packaging begins when DNA associates with histones to form nucleosomes (“beads on a string” in classic EM language), then folds into higher-order chromatin organization inside the nucleus.