nucleosome

biology

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June 17, 2026

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A nucleosome is a fundamental unit of chromatin, the complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. It consists of a segment of DNA wound around a core of eight histone proteins (two molecules each of H2A, H2B, H3, and H4). This bead-like structure, with DNA wrapped around the histone octamer, is crucial for packaging the cell's extensive DNA into the small volume of the nucleus.123

Nucleosomes not only help compact DNA but also play a role in regulating gene expression by influencing the accessibility of DNA to the cellular machinery involved in reading genetic information. The fifth histone, H1, binds to the DNA where it enters and leaves the nucleosome, further stabilizing the structure and contributing to the coiling of nucleosomes into a more compact chromatin fiber.13

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cell
Nucleosomes: the subunits of chromatin
…beadlike structure is called the nucleosome. The DNA enters and leaves a series of nucleosomes, linking them like beads along a string in lengths that vary between species of organism or even between different types of cell within a species. A string of nucleosomes is then coiled into a solenoid…
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…beadlike structure is called the nucleosome. The DNA enters and leaves a series of nucleosomes, linking them like beads along a string in lengths that vary between species of organism or even between different types of cell within a species. A string of nucleosomes is then coiled into a solenoid…
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cell
The differentiated state
…complexed into repeating structures called nucleosomes, each of which contains eight molecules of histone. Active genes are found in parts of the DNA where the chromatin has an “open” configuration, in which regulatory proteins are able to gain access to the DNA. The degree to which the chromatin opens depends…
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…complexed into repeating structures called nucleosomes, each of which contains eight molecules of histone. Active genes are found in parts of the DNA where the chromatin has an “open” configuration, in which regulatory proteins are able to gain access to the DNA. The degree to which the chromatin opens depends…
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histone
…form nucleoprotein complexes known as nucleosomes. Each nucleosome is made up of an octamer of two copies of four different histone proteins, designated H2A, H2B, H3, and H4. DNA winds around groups of histones, helping to organize it into a compact structure known as chromatin. A so-called linker histone, H1,…
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…form nucleoprotein complexes known as nucleosomes. Each nucleosome is made up of an octamer of two copies of four different histone proteins, designated H2A, H2B, H3, and H4. DNA winds around groups of histones, helping to organize it into a compact structure known as chromatin. A so-called linker histone, H1,…
Read More