If E. coli bacteria are grown in the absence of lactoseMultiple Choicethe repressor will not bind the operator, thus allowing transcription of the lac operon genes.the repressor will bind the operator, thus allowing transcription of the lac operon genes.the repressor will not bind the operator, thus preventing transcription of the lac operon genes.the repressor will bind the operator, thus preventing transcription of the lac operon genes.No answer is correct.

The lac operon in E. coli is a coordinately controlled set of genes required for lactose metabolism. The operon and its associated regulatory sequences are shown in the following diagram.Two parallel horizontal lines are shown with a break between the first segment and the second segment. The first segment has a box labeled promoter and a box labeled lacI followed by an unlabeled black box. The second segment begins with an unlabeled black box, followed by a box labeled CAP site, a box labeled promoter, a box labeled operator and then 3 boxes with a bracket above them with the caption structural genes. The 3 boxes are labeled lacZ, lacY and lacA.The function of each locus shown in the diagram is listed in the table below.Part FunctionPromoter Binding site for RNA polymeraselacI Gene encoding the lac repressor proteinCAP site Binding site for the catabolite activator proteinOperator Binding site for the lac repressor proteinlacZ Gene encoding the beta-galactosidase proteinlacY Gene encoding the lactose permease proteinlacA Gene encoding the galactoside transacetylase proteinThe activity of the lac operon is influenced by the availability of lactose and glucose in the cellular environment. In the presence of lactose, the lac repressor protein is released from the operator, which allows the structural genes to be transcribed at a low level. If glucose (the preferred carbon source) is absent during this time, the catabolite activator protein binds to the CAP site, causing the structural genes to be transcribed at a higher level.Which of the following is the most likely result of a mutation in the lac repressor protein that prevents binding to the operator?Choose 1 answer:Choose 1 answer:(Choice A, Checked)   The catabolite activator protein will not bind to the CAP site, even in the absence of glucose.AThe catabolite activator protein will not bind to the CAP site, even in the absence of glucose.(Choice B)   The lacI gene will be highly expressed, even in the presence of glucose.BThe lacI gene will be highly expressed, even in the presence of glucose.(Choice C)   The structural genes will not be transcribed, even in the presence of lactose.CThe structural genes will not be transcribed, even in the presence of lactose.(Choice D)   The lactose permease protein will be produced, even in the absence of lactose.DThe lactose permease protein will be produced, even in the absence of lactose.

Regulation of bacterial operons by inducers, e.g. lactose, exhibits which of the following properties?(1) Inducer binds to the repressor and __________(2) Inducer effect on RNA polymerase binding to the promoter: ___________(3) Repressor produced by:Select one:A.(1) Activates the repressor, (2) Enhances, (3) A separate geneB.(1) Inhibits the repressor, (2) No effect, (3) A separate geneC.(1) Inhibits the repressor, (2) Inhibits, (3) Genes of the operonD.(1) Activates the repressor, (2) Inhibits, (3) A separate geneE.(1) Activates the repressor, (2) Enhances, (3) Genes of the operon

Lactose or its analogues act as positive regulators of Lac operon by:Select one:a. Attaching to I gene and preventing its expressionb. Binding to repressor subunits so that the repressor cannot attached to operator locus.c. Increasing the synthesis of catabolic gene activator protein.d. Attaching to promoter region and facilitating the biding of RNA polymerase

In an inducible bacterial operon, what is the effect of the binding of the inducer molecule to the repressor protein? Inhibits the binding of the repressor protein to the operator and activates gene transcription Promotes the binding of the repressor protein to the operator and blocks gene transcription Has no effect on the binding of the repressor to the operator and transcription Inhibits the binding of DNA polymerase to the operator Promotes the splicing of the mRNA

When both CAP and the lac repressor are bound as shown in the figure below, what happens to the genes in the lac operon?Group of answer choicesThe genes are transcribed once, but after that the repressor protein displaces the activatorThe genes are transcribed at a high level, because the activator will block the activity of the repressorThe genes are transcribed at a very low level, because when the repressor is bound to DNA it blocks RNA polymerase.The genes are transcribed half of the time, because the activator and repressor will each "win" half of the time