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How does the active CAP induce expression of the genes of the lactose operon?
The active CAP (catabolite activator protein) binds to the CAP site near the promoter of the lactose operon. This binding helps RNA polymerase bind to the promoter, leading to enhanced transcription of the genes in the lactose operon. This process is a part of positive regulation in response to low glucose levels and presence of lactose.
What does the promoter of the lac operon sac do?
The promoter of the lac operon helps initiate the transcription of the lac genes. It is where RNA polymerase binds to start transcribing the mRNA for the lacZ, lacY, and lacA genes. The Lac operon is a system in bacterial cells that regulates the expression of genes involved in lactose metabolism.
How does active CAP induce expression of the genes of the lactose operon?
Active CAP binds to the CAP site in the promoter region of the lactose operon. This binding helps RNA polymerase to efficiently initiate transcription of the genes in the operon, leading to their expression. The presence of cAMP is necessary for CAP to be active and bind to DNA.
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
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.
What is the role of the lac operator in gene regulation?
The lac operator is a DNA sequence that acts as a binding site for a repressor protein in gene regulation. When the repressor protein binds to the lac operator, it prevents the expression of genes involved in lactose metabolism. This helps regulate the production of enzymes needed for lactose utilization in bacteria.
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.
The obvious advantage of the lactose operon system is that?
it allows bacteria to regulate the expression of genes involved in lactose metabolism in response to lactose availability. This enables efficient utilization of lactose as an energy source only when needed, conserving cellular resources when lactose is not present in the environment.
When does the induction of the lac operon occur?
The induction of the lac operon occurs when lactose is present in the environment and glucose is limited. The presence of lactose leads to the activation of the lac repressor protein, allowing RNA polymerase to bind to the promoter region and transcribe the genes involved in lactose metabolism.
What happens to the expression of the lacl gene if lactose is not available in the cell?
The expression of the lacI gene will remain active in the absence of lactose. As a repressor gene, lacI produces a protein that binds to the operator site on the lac operon, preventing RNA polymerase from transcribing the lacZ, lacY, and lacA genes. This leads to low expression of the lac operon when lactose is not present.
