BIO 213 Study Guide - Operon, Repressor, Nucleoid
Document Summary
The dna of prokaryotes is organized into a circular chromosome supercoiled in the nucleoid region of the cell cytoplasm. Proteins that are needed for a specific function are encoded together in blocks called operons. In prokaryotic cells, there are three types of regulatory molecules that can affect the expression of operons: repressors, activators, and inducers. Repressors are proteins that suppress transcription of a gene in response to an external stimulus, whereas activators are proteins that increase the transcription of a gene in response to an external stimulus. Inducers are small molecules that either activate or repress transcription depending on the needs of the cell and the availability of substrate. The regulatory region includes the promoter and the region surrounding the promoter, to which transcription factors can bind. Transcription factors influence the binding of rna polymerase to the promoter and allow its progression to transcribe structural genes.
