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The fundamental histone-containing structural subunit of eukaryotic chromosomes. In most eukaryotic organisms, nuclear deoxyribonucleic acid (DNA) is complexed with an approximately equal mass of histone protein. The nucleosome is organized so that the DNA is exterior and the histones interior. The DNA makes two turns around a core of eight histone molecules, thus forming a squat cylinder 11 nanometers in diameter and 5.5 nm in height. A short length of linker or spacer DNA connects one nucleosome to the next, forming a nucleosomal chain that has been likened to a beaded string. This basic structure is found in all forms of chromatin. Nucleosomes have been found in all eukaryotic organisms examined, the only exceptions being some sperm nuclei and the dinoflagellate algae.

A chain of adjacent nucleosomes is approximately sixfold shorter than the DNA it contains. Moreover, chains of nucleosomes have the property of self-assembling into thicker fibers in which the DNA packing ratio approaches 35:1. These observations, and the lack of any obvious catalytic activity, have led to the assumption that the primary function of the nucleosome consists of organizing and packing DNA. See Chromosome, Deoxyribonucleic acid (DNA), Gene

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


(cell and molecular biology)
A morphologically repeating unit of deoxyribonucleic acid (DNA) containing 190 base pairs of DNA folded together with eight histone molecules. Also known as v-body.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Figures 6(a)-6(d) show the micro-Raman spectra of (a) surface of metallic particle, (b) silicon substrate, (c) surface of core particle, and (d) particle on the core particle, respectively.
Subsequent x-ray crystallographic analyses have confirmed his electron microscopy findings as advances in methodology and crystallographic resolution have revealed more and more details of the structure of nucleosomel core particles (2).
[10] also assert that as the stabilizing layer thickness relative to the core particle size increases, compressibility of the layer increases which decreases the interaction strength and decreases n.
* Accucore HPLC--Containing solid core particles, these are engineered to a diameter of 2.6 [micro]m and a narrow particle size distribution for highspeed, high-resolution separations.
In this process, the core particles are first suspended in the liquid coating material.
The smallest core particles were obtained at the highest S/W ratio, i.e., S/W = 1.46.
More importantly, the Ti[O.sub.2] layer of one FST5 particle had no magnetic core, which indicates that the nonmagnetic core particles could be generated as the coating times increased.
Containing solid core particles, which are engineered to a diameter of 2.6 pm and an average particle size distribution (D90/10) of 1.12, the columns allow high-speed, high-resolution separation with low backpressures.
The core particles and supercritical [CO.sub.2] (SC-[CO.sub.2]) dissolved with shell materials can be ejected from the nozzle together.
Whether for coating base powder particles for taste masking, improvement of flow characteristics, protection of core particles, controlled release effect or controlled dissolving time, the Hosokawa Turbulizer horizontal paddle mixer with its fully adjustable paddles is flexible in operation to suit most process requirements.
Kenaf core particles are used to make panels with easy processing and in comparison to commercially available insulation panels, making it a potential raw material for low density insulation panels [20].
The results suggest that paraffin-micro encapsulated red phosphorus particles show a lower moisture absorption ratio within the experimental conditions of the extraction column and nozzle temperature of 120 [degrees] C, extraction column pressure of more than 16 MPa, and a mass flow of core particles (0.5 g/min).