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Is the lac operon the only example of genes regulated by repressor proteins?
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∙ 12y ago
False
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∙ 12y ago
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Why is the tryptophan operon turned off in the presence of tryptophan?
Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.
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 . .
What genes is not a part of the lac operon?
repressor gene
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.
The role of a metabolite that controls a repressible operon is to?
The role of a metabolite that controls a repressible operon is to
Why is the tryptophan operon turned off in the presence of tryptophan?
Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.
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
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 . .
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.
Where is the repressor structure coded?
operon
What region of the operon does the repressor bind to?
I assume you mean the lac operon. The repressor binds upstream of the gene(s) in the regulatory gene region.
The operon segment composed of the gene that codes for a protein repressor is called the?
The operon segment composed of the gene that codes for a protein repressor is called the regulatory gene. This gene produces the repressor protein that can bind to the operator region of the operon, preventing transcription of the structural genes when the repressor is bound.
What genes is not a part of the lac operon?
repressor gene
Which region of the operon does the repressor bind to?
It binds to the operator.
How does the repressor protien prevent transcription?
it blocks the promoter from the operon.
What acts as a co-repressor to block transcription of the tryptophan operon?
Tryptophan
