Name:Prokaryotic Gene Regulation: Discussion #9 worksheet1. What is gene regulation? What is the goal of gene regulation?Ensuring that the right genes are expressed only at the correct time and place. It can control how much functional protein is in the cell. Goal is to control the specificity of transcription of a group of genes. 2. What is an operon? What is the goal of an operon (why have them)? What is the product of transcription of an operon?The operator, promoter, genes they control and terminator constitute an operon. Operons allow genes to be coordinately controlled. Grouping genes of related function into one transcription unit allows single “on-off switch” to control the whole cluster of functionally related genes. 3. A typical operon will have at least the following components/DNA sequences. For each component, specify the general role of each in the operon and which if any proteins will bind to it.Promoter: starts transcription of mRNA strand; where the RNA polymerase attaches Operator: operons switch for controlling transcription; can bind to repressor which prevents transcriptionGenes: genes grouped together for a specific function; regulate enzyme productionTerminator: ends the transcription unit4. The trp operon contains 5 genes (trp a, trp b, trp c, trp d and trp e), which code for the enzymes in the metabolic pathway necessary to make tryptophan in the E. coli cell. The ‘goal’ of the trp operon is to make tryptophan = when the trp operon is ‘on’ the cell will make the enzymes to make tryptophan and will thus make tryptophan. RNA Pol, the trp repressor protein and tryptophan control expression of thetrp operon. a. When tryptophan is available from the environment, would you expect the trp operon to be ‘on’ or ‘off’? ____off___________________b. Explain your answer to (a) by describing where/how you would expect to find RNA Pol and the trp repressor protein in this scenario (trp + environment).RNA pol would not bind to the promoter and transcription would not occur. Tryptophan binds to the trp repressor when it is available by the environment and attaches at an allosteric site changing the repressor protein to an active form that can attach to the operator, turningthe operon off. c. When tryptophan is not available from the environment, would you expect the trp operon to be ‘on’ or ‘off’? _______on________________d. Explain your answer to (c) by describing where/how you would expect to find RNA Pol and the trp repressor protein in this scenario (trp – environment).RNA pol is attached to the promoter and transcription occurs. The trp repressor protein is attached to its own promoter not on the operon. It is inactive since the corepressor (tryptophan) is not attached. TerminatorGene 4Gene 3Gene 2Gene 1operatorpromoterpromoter operator trpE trpD trpC trpB trpA Terminatore. Is the trp operon inducible (turned on when needed) or repressible (turned off when not needed?) ___________repressible_______________f. Is the trp operon an example of positive or negative transcriptional regulation? _______________________5. The lac operon contains 3 genes (lacZ, lacY and lacA), which code for the enzymes involved in the uptake and breakdown of the disaccharide lactose into two monosaccharides. The ‘goal’ of the lac operon is to breakdown lactose into galactose and glucose (so they can be used as an energy source for glycolysis) = when the lac operon is ‘on’ the cell will make the enzymes to breakdown lactose and thus breakdown lactose. RNA Pol, the lac repressor protein, CAP, lactose, glucose and cAMP control expression of the lac operon.a. Would you expect the lac operon to be ‘on’ or ‘off’, high or low when there is glucose available, but no lactose? ______off_________________b. Explain your answer to (a) by describing where/how you would expect to find RNA Pol, the lac repressor protein and the CAP protein in this scenario (glucose +, lactose - environment).The repressor is active and transcription stops for the lac operon. RNA pol cannot bind and the cap protein is scarce since the glucose is present in the cell. c. Would you expect the lac operon to be ‘on’ or ‘off’, high or low when there is lactose available, but no glucose? ___________on____________d. Explain your answer to (a) by describing where/how you would expect to find RNA Pol, the lac repressor protein and the CAP protein in this scenario (glucose -, lactose + environment).The cell will use the lac operon. The cAMP level is high and it binds to the CAP activating the lac operon. RNA pol binds to the promoter and transcription occurs. e. Would you expect the lac operon to be ‘on’ or ‘off’, high or low when there is both lactose and glucose available? ___off____________________f. Explain your answer to (a) by describing where/how you would expect to find RNA Pol, the lac repressor protein and the CAP protein in this scenario (glucose +, lactose + environment).The cell prefers to use glucose when it is available, so the cAMP concentration falls, and CAP detaches from the operon. RNA pol binds less efficiently to the promoter and transcription of the lac operon proceeds at only a low level. g. Would you expect the lac operon to be ‘on’ or ‘off’, high or low when there is neither lactose or glucose available? ________off_______________h. Explain your answer to (a) by describing where/how you would expect to find RNA Pol, the lac repressor protein and the CAP protein in this scenario (glucose -, lactose - environment).IF neither is present, the repressor will bind to the operator and prevent transcription. CAP protein is available to bind to CAP, but since the repressor is bound transcription cannot occur and the lac operon is off. e. Is the lac operon inducible (turned on when needed) or repressible (turned off when not needed?) _______inducible___________________f. Is the lac operon an example of positive or negative transcriptional regulation? _______negative______________operatorCPS TerminatorlacZ