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What is the mechanism by which the presence of glucose inhibits the lac operon?
Wiki User
∙ 7y ago
The mechanism by which the presence of glucose inhibits the arabinose operon is catabolite repression. The lac operon is responsible for the metabolism of glucose.
Wiki User
∙ 9y ago
Wiki User
∙ 9y agoThe mechanism by which the presence of glucose inhibits the arabinos operon is catabolite repression. It is an important process in the global control system of various microorganisms.
Wiki User
∙ 12y agoCatabolite repression
Wiki User
∙ 13y agoinduction
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What would happen to the lac operon if a bacterium were growing in the presence of both glucose and lactose?
The regulatory portion of the operon is the only portion that would be transcribed.
The positive control of the lactose operon in bacteria is what?
Catabolite repression is the positive control of the lactose operon in bacteria. Glucose is metabolized initially and when depleted, the lactose.
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.
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
Explain how cyclic AMP and catabolite activator protein are affected by glucose concentration?
Cyclic AMP accumulates when the glucose concentration is scarce. If the glucose concentration increases, the cAMP concentration falls, and without it, CAP (catabolite activator portein) detaches from the operon and becomes inactive.
What would happen to the lac operon if a bacterium were growing in the presence of both glucose and lactose?
The regulatory portion of the operon is the only portion that would be transcribed.
What is a clue that the lac operon is on?
The lac operon uses a two-part control mechanism to ensure that the cell expends energy producing the enzymes encoded by the lac operon only when necessary. In the presence of lactose, the lac repressor halts production of the enzymes encoded by the lac operon.
How is lac operon different from trp operon?
1. in lac operon; gene activity is induced when lactose is present in the medium, whereas in case of trp operon, repression of the gene activity takes place in presence of tryptophan in the medium. 2. lac operon spans about 4-6kb...whereas trp operon spans abut 7kb. 3. lac operon helps in the breakdown of lactose into glucose and galactose, to generate energy( catabolic pathway ) in case of trp operon, it helps in the synthesis of enzymes required for the formation of the amino acid Tryptophan( anabolic pathway ). 4. lac operon is an example of positive regulation ; and trp operon is an example of negative regulation. Trp operon is also regulated by other mechanism called attenuation while no such even occurs in lac operon . .
When does the induction of the lac operon occur?
The lac operon is most active when glucose levels are low and lactose is present.
When is lac operon most active?
The lac operon is most active when glucose levels are low and lactose is present.
The positive control of the lactose operon in bacteria is what?
Catabolite repression is the positive control of the lactose operon in bacteria. Glucose is metabolized initially and when depleted, the lactose.
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.
An operon is composed of?
An operon is a group of genes that operate together.Operon- a functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter.Operons are clusters of genes consisting of one operator and promoter. There are a lac operon, which is responsible for metabolism of glucose. And there is also the Trp operon, which is responsible for synthesising tryptophan.
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 environmental factor causes the lac operon to turn on?
In the lac operon model, lactose acts as in inducer molecule. In the presence of lactose, the molecule binds to the repressor protein. This repressor-lactose complex is unable to bind to the promoter. When the promoter is not occupied, RNA pol - II binds to it and begins transcribing the structural genes located downstream. Thus, the lac operon is turned on in the presence of lactose.
What does the E coli the lac operon controls?
When the lac operon controls the expression of proteins in the E.coli cell that can break down lactose into two sugars, glucose and galactose. When lactose is present, it binds to the repressor that typically sits on the lac operon, changing the repressor's conformation such that it can no longer bind to the lac operon. Because of this, RNA polymerase can now transcribe the gene into mRNA, which in turn is translated into the proteins that can break down lactose.
What does the E coli the lac operon control?
When the lac operon controls the expression of proteins in the E.coli cell that can break down lactose into two sugars, glucose and galactose. When lactose is present, it binds to the repressor that typically sits on the lac operon, changing the repressor's conformation such that it can no longer bind to the lac operon. Because of this, RNA polymerase can now transcribe the gene into mRNA, which in turn is translated into the proteins that can break down lactose.
