Dictionary > Histone

Histone

Definition
noun, plural: histones
A water-soluble alkaline protein in the nucleus, and from where the DNA tightly coils around to form the nucleosome
Supplement
Histone is a water-soluble alkaline protein. It is rich in lysine and arginine. There are five major families of histones: H1, H2A, H2B, H3, and H4. The first is a linker whereas the other four are core.
Histones are the proteins in the nucleus serving as spools from where the DNA tightly coils around at. Histones form a core by which the DNA wounds around to form the fundamental structural unit of chromatin, the nucleosome. A nucleosome is made up of around 200 base pairs and eight histones (i.e. histone octamer). These histones include two of each of H2A, H2B, H3 and H4. The histone octamer through which DNA coils around facilitates the packing of a large genome into the nucleus. Without the histone core the genome would be too lengthy to fit into the nucleus. The length of the DNA in a human diploid cell is about 1.8 meters whereas the nucleus has about a diameter of 10 ┬Ám. Apart from compacting DNA strands, the histones are also associated with chromatin regulation. They undergo modifications for several biological processes, e.g. DNA repair, spermatogenesis in meiosis, and chromosome condensation during mitosis.
See also:


You will also like...

Plant biology
Plant Biology

Plantlife can be studied at a variety of levels, from the molecular, genetic and biochemical level through organelles, c..

Physiological Homeostasis
Physiological Homeostasis

Homeostasis is essential to maintain conditions within the tolerable limits. Otherwise, the body will fail to function p..

Schematic diagram of bacterial lactose operon
Gene Action – Operon Hypothesis

Learn how the way genes control and determine every aspect of the body. This lesson uses lac operon as an example. ..

..

Biosecurity and Biocontrol
Biosecurity and Biocontrol

This lesson explores the impact of biosecurity threats, and why they need to be identified and managed. Examples to incl..

Principles of Hormonal Control Systems
Principles of Hormonal Control Systems

Hormones are essential in the regulation of the activity of the various biological systems of the human body. The ineffi..

Lights' Effect on Growth
Lights’ Effect on Growth

This tutorial elaborates on the effect of light on plant growth. It describes how different plants require different amo..