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see chromosomechromosome
, structural carrier of hereditary characteristics, found in the nucleus of every cell and so named for its readiness to absorb dyes. The term chromosome
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chromosome substance found in the nuclei of plant and animal cells. Chromatin stains intensively with nuclear stains and, at the time of cell division, forms certain visible structures in the chromosomes. The term was introduced in 1880 by the German histologist W. Flemming. Present-day cytologists generally understand chromatin to be chromosomal material of the cell nucleus in interphase (between its successive divisions), since chromosomes in that period of cell cycle are not easily detected under the microscope. Chromatin is made up of deoxyribonucleic acid (DNA, 30–40 percent), ribonucleic acid (RNA), histones, and nonhistone proteins. The main structural components of chromatin are deoxyribonucleoprotein strands measuring 100–200Å in diameter and based on, according to most investigators, one molecule of DNA.

American scientists have proposed two models of the fine structure of a primary chromatin strand: super-coil (J. F. Pardon and M. H. F. Wilkins, 1972) and spheroid (R. D. Kornberg, 1974; A. L. Olins and D. E. Olins, 1974). The spheroid model, which has been better substantiated experimentally, supposes that the primary chromatin strand is a flexible chain of repeating subunits—that is, nucleosoma—which is a bent DNA section of 150–200 pairs of nucleotides and a complex of eight histone molecules.

Genetically active chromatin (euchromatin) is differentiated from inactive chromatin (heterochromatin). The cell nuclei of females of many organisms—especially mammals (including man)—contain dense masses of chromatin called sex chromatin. Such masses, which are not present in males, apparently are formed in females by inactive sections of the sex chromosomes, mainly from the heterochromatin of one of the paired X chromosomes.



The deoxyribonucleoprotein complex forming the major portion of the nuclear material and of the chromosomes.


Cytology the part of the nucleus that consists of DNA and proteins, forms the chromosomes, and stains with basic dyes
References in periodicals archive ?
Now is well established by several lines of evidence that chromatin modifications and especially gene epigenetic regulation can also influence plant hormone signaling.
In the case of heat shock, sustained stress over multiple generations resulted in the altered chromatin state being inherited by subsequent generations as well.
Further, most important findings of our study were that after I/R injury hepatocytes chromatin condensation were increased as compared to sham operated control rats.
Key words Assisted reproduction techniques--DNA fragmentation--DNA integrity--oxidative stress--sperm chromatin structure assay
There was no significant difference in the percent damaged chromatin between the HTF control group and the Pre-Seed group.
NRC-PBI's partnership with Chromatin will increase our scientific and technical capabilities in canola improvement and diversification," said Dr.
What he learns could help cancer researchers, he says, because of the indication that animals and humans also use the chromatin remodeling factor protein to turn particular genes on and off.
1 EMBO Journal, for example, Wolffe and a colleague describe how one egg protein induces the nucleus of an adult frog cell to shed certain chromatin proteins and incorporate others more suited to an egg nucleus.
Therefore, the older tests were gradually replaced by more accurate tests such as sperm nucleus and chromatin evaluation.
Of these, five are known to be in genes involved in the regulation of the tightly packed form of DNA called chromatin - a proportion that is much higher than would have been expected by chance, according to Chesi.
Now a team of researchers from Boston Children's Hospital's Program in Cellular and Molecular Medicine report that mice lacking a neutrophil enzyme called PAD4, which helps unravel the chromatin in neutrophils' nuclei, cannot form DVTs.
Previous studies at Penn State and other research institutions led to the discovery of chromatin enzymes - proteins that act to turn specific genes on or off by binding to the nucleosome.