polytene chromosome - large chromosome resulting from repeated DNA replication and alignment of homologs in the absence of mitosis; found in salivary glands and some other tissues of dipteran insects.
Polytene
The term proposed by Koller (1935) to describe the multistranded condition (Gk. polys, many; tania, ribbon) of the chromosomes found in certain specialized tissues such as the salivary glands of Drosophila.
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Chromosome ...
Polytene chromosomes are subdivided into some 5,000 dark bands separated by light interbands. Genes are located in both, but those in the interband regions seem to be more active.
Polytene chromosomes are seen in the salivary glands of fruit fly larvae and the larvae of some other insects.
polytene chromosomes Chromosomes in the somatic cells of some insects in which the chromatin replicates repeatedly without undergoing mitosis.
polyunsaturated fat A fat having several to many double bonds between carbon atoms.
The polytene banding of the 'picture wing' group, the best-studied group of Hawaiian drosophilids, enabled Carson to work out the evolutionary tree long before genome analysis was practicable.
The point at which polytene chromosomes appear to be attached together.
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An additional reason for the fruit fly's value as a model organism is the giant polytene chromosomes found in cells of the insect's salivary glands.
(Science: cell biology, genetics) The largest puffs seen on the polytene chromosomes of diptera are called balbiani rings after the nineteenth century microscopist who first described polytene chromosomes.
 See also: Chromosome, Chromosomes, DNA, Cells, Cell
  
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