# chromatin

/kɹˈəʊmɐtˌɪn/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/chromatin
Updated: 2026-05-26

## Definition

the material that makes up the chromosomes in a cell. It is a mix of DNA and proteins that help keep the genetic information organized.

For teachers: the complex of DNA and proteins that forms the chromosomes within the nucleus of eukaryotic cells. It exists in two forms: euchromatin, which is less condensed and transcriptionally active, and heterochromatin, which is more condensed and transcriptionally silent.

## Examples

- Chromatin condenses into chromosomes during cell division.
- The structure of chromatin allows the long DNA molecules to fit inside the tiny nucleus of a cell.
- Epigenetic modifications to the histone proteins within chromatin can alter gene expression without changing the underlying DNA sequence, effectively turning genes on or off as needed.

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