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chromosome puffA localised separation of polytene chromosomes (e.g., chromosomes of Drosophila melanogaster) that represents a site of active RNA synthesis—i.e., transcription—which, when very large, is known as a Balbiani ring.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
puffa cloudy area visible on specific CHROMOMERES of SALIVERY GLAND CHROMOSOMES at certain times. Chromosome puffs contain DNA and RNA and are thought to represent gene TRANSCRIPTION. This idea is reinforced by the fact that such puffs occur at regular intervals, suggesting that GENE SWITCHING is in operation.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005