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cell biology Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living an ...
, chromosome territories are regions of the nucleus preferentially occupied by particular
chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...
s.
Interphase Interphase is the active portion of the cell cycle that includes the G1, S, and G2 phases, where the cell grows, replicates its DNA, and prepares for mitosis, respectively. Interphase was formerly called the "resting phase," but the cell i ...
chromosomes are long
DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
strands that are extensively folded, and are often described as appearing like a bowl of
spaghetti Spaghetti () is a long, thin, solid, cylindrical pasta.spaghetti
Dictionary.com. Dictionary.com Una ...
. The chromosome territory concept holds that despite this apparent disorder, chromosomes largely occupy defined regions of the nucleus. Most
eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...
s are thought to have chromosome territories, although the budding
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
'' S. cerevisiae'' is an exception to this.


Characteristics

Chromosome territories are spheroid with diameters on the order of one to few micrometers. Nuclear compartments devoid of DNA called interchromatin compartments have been reported to tunnel into chromosome territories to facilitate molecular diffusion into the otherwise tightly packed chromosome-occupied regions.


History and experimental support

The concept of chromosome territories was proposed by Carl Rabl in 1885 based on studies of Salamandra maculata. Chromosome territories have gained recognition using fluorescence labeling techniques ( fluorescence in situ hybridization). Studies of genomic proximity using techniques like chromosome conformation capture have supported the chromosome territory concept by showing that DNA-DNA contacts predominantly happen within particular chromosomes.


See also

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References

{{reflist Molecular biology Nuclear organization