chromosome puff

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chromosome puff

a band of accumulated chromatin located at a specific site on a giant chromosome. It is indicative of gene activity, specifically DNA and RNA synthesis at that site. Such bands appear at certain chromosomal locations within a given tissue at specific developmental stages in insects and are significant in the study of the mode of genetic transmission.

chromosome puff

A 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.

chromosome puff

or

puff

a 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.