Gene Regulation Why Gene Regulation? for maximum efficiency a cell needs to be able to control the quantities of gene products produced some are needed in large quantities ribosomal proteins some are needed in only small quantities many enzymes respond to the environment by turning on (or off) specific genes or groups of genes the Lac operon, heat shock genes turn genes on and off in the correct temporal pattern phage or viral infection, development There are three main levels of gene regulation Control of RNA abundance (transcriptional regulation) initiation, elongation, stability Control of protein synthesis (translational regulation) ribosome binding, rate of translation, termination Control of protein activity stability, modification, allosteric effects Types of regulation constituitive, inducible or repressible positive, negative, both positive and negative and with gene sets there is also coordinate and temporal regulation some examples of these in regulatory circuits are the lac operon, the trp operon and the lysogenic and lytic genes of lambda the lac operon is an inducible system that is under both negative and positive regulation the trp operon is a repressible system with two types of negative control the lytic genes of lambda show how genes can be temporaly regulated [ Biol 207 ] [ Bell ] [ CSU Chico ] [ Library ] This document is maintained by: Jeff Bell Last Update: Wednesday, August 12, 1998