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What is the name of the DNA sequence that is located newr the promoter of the lactose operon and regulates the expression of the operon in E.Coli?
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How does active CAP induce expression of the genes of the lactose operon?
It stimulates the binding of RNA polymerase to the promoter.
How does the active CAP induce expression of the genes of the lactose operon?
It stimulates the binding of RNA polymerase to the promoter.
Where on the lac operon does transcription take place?
The lac operon encodes enzymes required in the digestion and transport of lactose. Transcription is activated when there is lactose in the cellular environment, and RNA polymerase binds to the promoter region of the operon, and activates the expression of lacA, lacZ and lacY.
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.
Is operon the sequence of bases on a gene that does not code for protein?
operon is a group of genes regulated by a single promoter and operator. . . generally all the genes (structural genes of a particular operon) regulate a specific metabolic pathway. . (eg : lac operon in bacteria; where 3 genes are regulated by a single promoter sequece which help in the catabolism of lactose). . . if you have any doubts mail me at vegi.chaitanya@gmial.com
What is the role of lactose in regulating lac operon expression?
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 must happen for transcription of the lac operon genes to take place?
Lac operon is a set of genes that regulates the digestion of lactose. In absence of lactose in the medium, the repressor protein binds to the operator that inhibit the transcription of structural genes such as beta galactosidase, lactose permease and transacetylase. This makes sure to avoid the enzyme synthesis when there is no need!Conversely, when the lactose present in the medium, an isomer of lactose called allolactose bind to the repressor protein, the conformational change in the repressor let it to detach from repressor hence the RNA polymerase can transcribe the structural gene. Although this may be enough for synthesis of structual gene the system is tightly regulated by a protein called CAP (catabolite activator protein) and glucose.Glucose is a preferred source of energy for cell when this desirable source is present, lactose need not be used as a energy resource. What happens is there will be low level of cAMP when there is high amount of glucose and this keeps CAP inactive.When there is low glucose levels, the cAMP would be higher, that binds to CAP to make it active, which in turn binds to the promoter that enhance the transcription of structural genes.Thus, for efficient transcription lac operon structural genes, lactose must be present where glucose must be absent.
In Figure 84 which model of the lac operon correctly shows RNA polymerase lactose and repressor protein when the structural genes are being transcribed?
regulatory promoter oerator
What happens when lactose is e coli's only food source?
The genes that produce the enzymes needed to break down lactose are not expressed.
Is operon proteins?
Operon is not a protein. It is a segment of DNA that has cluster of genes controlled by the elements such as promoter, operator. Lac operon is a classic example where it regulate the utilization of Lactose in the medium.
What happens to the expression of the lacl gene if lactose is not available in the cell?
there is no change--the lacl gene is constitutively expressed
What is lac operon in E. coli?
The lac operon is a place on the DNA that binds to the DNA to stop the production of the RNA sequence to code for lactase (breaks down lactose) or binds to lactase to let the production of the RNA sequence to proceed.
