Bacteria caq

💊 Bacteria Created Tags Advantages of operon Allow bacteria to coordinately regulate the expression of a group of genes that encode proteins with a common functional goal Ensure that all proteins necessary to metabolise a particular compound are under a single promoter so that these genes are made turned off or turned on at the same time helping the bacteria to respond quickly to environmental changes (how operons allow for rapid response by bacteria to environmental change), providing a selective advantage Bacteria only produces enzymes when required, preventing waste of limited energy and resources which provides a selective advantage as they are able to respond quickly to changes in environment Different operant allow bacteria to utilise different types of carbon source/ a variety of sugars for their energy requirements For repressible systems only: When end product is abundant, synthesis would stop and operon can be repressed to minimise wastage and conserve resources and these resources can be redirected to other cellular processes important to bacterium How does lac operon works/ how the metabolism of lactose in bacterial cells is regulated Regulation of the metabolism of the lactose is done by lac operon With Lac ZYA under the control of one promote sequence which codes for enzymes/ August 7 , 2025 124 1 PM Bact er ia 1

proteins that hydrolyse lactose to allolactose(lac Z and transport lactose into the cell (lac Y Lac L gene codes for an active lac repressor which is complementary in shape and binds to the operator sequence, a repressor binding site When lactose is absent, there is basal transcription level as repressor is bound to the operator sequence, inhibiting RNA polymerase from binding to promoter When lactose is present and glucose is absent, lactose is transported into the cell by permease and is converted to allolactose by beta-galactosidase Allolactose acts as an inducer and binds to the allosteric site of lac repressor and changes the conformation of active lac repressor thereby inactivating it as it is no longer complementary to the operator sequence and thus dissociates from operator, no longer can bind to the operator This allows the binding of RNA polymerase to promoter and move downstream to transcribe the structural genes to form beta galactosidase, permease and transacetylase for metabolism of lactose ATP converted to cAMP by adenyl Cyclase and cAMP binds to Catabolite Activator Protein CAP to form cAMPCAP complex activating it which then binds to the CAP site upstream of promoter, increasing expression of Lac operon as it increases the affinity of RNA polymerase to promoter (relate to cell signalling where low glucose causes glucagon to bind to GPCR, eventually activating adenyl Cyclase) When glucose is present, it inhibits adenyl Cyclase which is responsible the conversion of ATP to cAMP, low levels of cAMP, lesser cAMP to bind to CAP, to form cAMPCAP complex amd activating i