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When the lac repressor binds to the O region, RNA polymerase is prevented from beginning the process of transcription. In effect, the binding of the repressor protein turns the operon "off" by preventing the transcription of its genes. (Prentice Hall Biology Book .....Chapter 12 page 310)
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∙ 14y ago
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∙ 12y agoIt turns off when the RNA polymerase is absent.
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∙ 9y agoThe lac operon refers to an operon needed for the transport and metabolism of lactose in Escherichia coli. It is switched off when the RNA polymerase binds to the operator.
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∙ 13y agoIac genes are turned off by repressors and turned on by the presence of lactose.
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∙ 13y agoby binding to an operator
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∙ 13y agothe operator
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∙ 14y agodna
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A lac repressor turns ff the lac genes by binding to?
A lac repressor turns off the lac genes by binding to the operator
What genes is not a part of the lac operon?
repressor gene
Is the lac operon the only example of genes regulated by repressor proteins?
False
What prevents e coli from expressing the lac genes in its DNA all of the time?
whenever the Lactose is present the lac genes in E.coli are turn on
What is the function of the operator locus of a Lac operon a. Binding with RNA polymerase b. Identifying the substrate lactose c. Producing messenger RNA d. Coding for represser e. Binding wit?
a. Incorrect, the promoter binds RNAP b. Incorrect, the lac repressor identifies lactose c. Incorrect, the RNAP produces mRNA from the lacY, lacZ and lacA genes d. Incorrect, lacI codes for the repressor e. ?? By the process of elimination this would be the correct answer but the operator locus binds the *lac repressor* ("wit" is an unfamiliar designation).
A lac repressor turns ff the lac genes by binding to?
A lac repressor turns off the lac genes by binding to the operator
What causes the lac genes in E. coli to turn off?
A lac repressor turns off the lac genes by binding to the operator.
What genes is not a part of the lac operon?
repressor gene
When lactose is present in bacterial does it prevent the blocking effect of the repressor protein and allow the transcription of lactose metabolizing genes?
Yes. A precursor to lactose binds to the repressor and prevents or relaxes its binding to the Lac operon.
How does lactose cause the lac operon to turn on?
The lac repressor protein has a binding site for lactose itself.
Is the lac operon the only example of genes regulated by repressor proteins?
False
What prevents e coli from expressing the lac genes in its DNA all of the time?
whenever the Lactose is present the lac genes in E.coli are turn on
What is the function of the operator locus of a Lac operon a. Binding with RNA polymerase b. Identifying the substrate lactose c. Producing messenger RNA d. Coding for represser e. Binding wit?
a. Incorrect, the promoter binds RNAP b. Incorrect, the lac repressor identifies lactose c. Incorrect, the RNAP produces mRNA from the lacY, lacZ and lacA genes d. Incorrect, lacI codes for the repressor e. ?? By the process of elimination this would be the correct answer but the operator locus binds the *lac repressor* ("wit" is an unfamiliar designation).
When the lac repressor protein binds to the?
The other region is the OPERATOR (O) e coli cells contains several copies of a DNA binding proteins known as the lac repressor, which can be bind to the O region your answer: Operator
When is gene expression blocked in the lac operon system?
The repressor protein blocks the genes from making mRNA.
Describe how E. coli uses the negative and positive control of the lac operon to economize on RNA and protein synthesis?
if a regulatory protein in its active state turns off the expression of the operon, the operon is said to be negatively regulated by the regulatory protein. if the regulatory protein in its active state truns on the operon, the operon is positively regulated by the regulatory protein. an operon regulated by a repressor is therefore negatively regulated, because the presence of the active repressor prevents transcription of that operon. in contrast, an operon regulated by an activator is positively regulated, because in its active state the activator protein turns on transcription of the operon under its control. the lac operon of E. coli repressor(lac repressor) is synthesized through the activity of the gene lac I, known as regulator gene. the active form of the lac repressor, is a tetramer that contains four copies of the gene I product. in the absence of the inducer, the repressor binds to the lac operator sequence, preventing RNA polymerase from binding to the promoter and transcribing the structural genes. thus the lac operon is negatively regulated associated with the lac operon, there is another site, 16 base pairs upstream of the promoter, which is used for a positive control of the gene expression. this site is called catabolic activator protein site or cyclic AMP(cAMP) protein site or catabolite gene activator(cga) site, because it is utilized for binding of CAP or cga to stimulate gene expression. CAP can bind to this site only when it is bound with cAMP. by binding to it, the CAP-cAMP complex exerts a positive control over the transcription process. it has an effect exactly opposite to that of repressor binding to an operator. yhe effector molecule cAMP determines the effect of CAP on lac operon transcription. presence of glucose inhibits the formation of cAMP and prevents it to bind to CAP
What is allolactose and how does it work?
Allolactose isca sugar, isomeric with lactose, that is the true inducer of the lac operon. An agent capable of activating specific genes. A molecule that inhibits the action of the repressor of an operon, preventing it from freely binding with the operator gene and disabling its function.
