University:
Swansea University
Course:
PM134 | Microbiology
Academic year:

2023
Views:

65

Pages:

3
Author:

Amal J.

LAC OPERONLactose is a disaccharide sugar synthesized by galactose andglucose Submits and has the molecular formula 42H 22011.Loutose makes up around 2-8% of milk (by mass)). The namecomes from $ lac (gen lactis), the Latin word for milk, plus theSuffsx - ose used to name sugare The compound is a white,water soluble, non hygroscopic solid with a mildly sweet taste.It is used in the food Industry.CH2OHlautose is sometimes refored to as OHCH2OHIatmilk sugar" because it is only found OH B 0 04naturally in the milk of mammals - including OHOHlows, goats and humans Milk from cans fig:- lactose.and goats is used to make cheese and yogheat ,but not allmilk products contan the same amount of lautor For examplehard cheers such as cheddar parmesan and swiss containvery little /no lactore. whereas milk, ice cream and yoghuertcontain higher amounts of lactose.Openon ModelThe basic concept about how gene regulation occurs ata level of trans oription in bacteria was provided by the classical model called 'THE OPERON MODELAn openn is a unit of bacterial gene expression andregulation which includes Structural genes, promoter and isacting regulatory sequences recognised by regulatory open geneproducts.ControlreginStructualThe lactore or lac openonIP(oxy20of E.coli is a cluster ofOperatorpromoterthree structural genes Regulatoryencoding proteins involved gene in lactose metabolism and theSites on the DNA involved in the the regulation of theoperon."Lac operon is an operon or a group of genes with asingle promoter that encode genes for the transport andmetabolion of lautose in E .coli and other bacteria" theconcept lac openon was proposed by Jawb andmond in 1961. Structure of Lac Operon.PromoterCAPsileOperator lacz lacy 1 lacApromotes RNA+polymerase-blocks RNA polymeroseCAPbindingRepresentRNA PolymerausInducible and Repressible System.Not all protein that a bouterial cell produce are needed all timesOr in same quantity. For eg: enzymes for breakdown of sugarsSunhas lautose @ may not be required if lautose is notpresent in cell's environment.If the cell produces encymes for the degradation of a particularCompound only when this compound is present in the Invironmethe System is called as INDUCIBLE SYSTEM for eg:-lac openanon the other hand if the cell produces enzymes for the Synthesiof a particular compound only when the compound is notpresent in the environment, the System is known asREPRESSIBLE SYSTEM. for eg:- Tryptophan operon.