Histone

Histones are basic proteins that bind DNA and organize it into chromatin. Their chemical modifications help regulate DNA accessibility and gene activity.

Nucleosome: A DNA segment wrapped around a core of histone proteins, forming the basic repeating unit of chromatin. Histone octamers form the protein core around which nucleosomal DNA wraps.
Chromatin: The complex of DNA, histone proteins, and other molecules that makes up chromosomes in eukaryotic cells. Histones are the principal proteins organizing DNA within chromatin.
Epigenetics: The study of heritable changes in gene activity that do not result from changes in DNA sequence. Histone modifications are a major mechanism of epigenetic regulation.
Histone variant: A histone protein variant that replaces a canonical histone in some nucleosomes and can confer distinct properties. Variants diversify histone function beyond the standard nucleosome components.
Albrecht Kossel: A German biochemist who characterized nucleic acids and basic nuclear proteins, including histones. His early studies helped establish histones as distinct components of cell nuclei.
Histone tail: A flexible, protruding region of a histone protein that can undergo chemical modification. Tail modifications alter chromatin interactions and recruit regulatory proteins.
Histone H2A: A core histone protein that pairs with H2B to form part of the nucleosome core. Two H2A–H2B dimers join the H3–H4 core in a canonical nucleosome.
Gene expression: The process by which information in a gene produces a functional RNA or protein. Histone-dependent access to DNA can influence transcription and gene output.
CENP-A: A histone H3 variant that marks centromeres and helps recruit kinetochore machinery. It replaces H3 in specialized centromeric nucleosomes.
Roger Kornberg: An American biochemist whose work established the nucleosome as a structural unit of chromatin. His 1974 model clarified how histones organize DNA into repeating particles.

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