Proposals to the problem of structural and functional organization of polytene chromosomes.

The concept of the structural and functional organization of polytene chromosomes is formulated. It is based on the following:Interbands are transcriptional active chromosome regions; they seem to be responsible for the base metabolism of the cell. The stability of these metabolic processes in the cells of different organs results in constancy of chromosome banding pattern. Thus, each functional state of the cell possesses its own banding pattern which may vary depending on activity level and degree of condensation of interbands.The band is considered not as a structural or functional unit, but as a region of the chromosome not involved in transcription at a certain point of time; a band may contain one or several genes.