Final answer:
Catabolite repression is the process by which presence of glucose inhibits the expression of operons for metabolizing other sugars in prokaryotic cells. It involves the interplay between cAMP levels and CAP protein binding to promoters like those of the lac operon.
Step-by-step explanation:
The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose in prokaryotic cells, particularly Escherichia coli, is a) Catabolite repression. This term refers to the cellular process where the presence of glucose inhibits the expression of operons involved in the metabolism of other sugars. Specifically, when glucose levels are high, catabolite repression ensures that the necessary genes for utilizing alternative sugar sources, such as lactose, are not expressed.
Catabolite repression works through a signaling molecule called cyclic AMP (cAMP) and its receptor, the CRP or CAP protein. Under conditions of low glucose, the cAMP levels within the cell increase. This cAMP binds to the CAP (cAMP receptor protein), which in turn can bind to the promoter of operons like the lac operon, facilitating transcription. However, when glucose is abundant, cAMP levels decrease, the CAP cannot bind to the promoter, and the genes are not transcribed, illustrating the principle of catabolite repression.