A lac repressor turns off the lac genes by binding to the operator.
The pressence of lactose.
The lac genes in E. coli are regulated by the lac operon, which is controlled by a repressor protein. The repressor binds to the operator region of the DNA, blocking the transcription of the lac genes. When lactose is present, it binds to the repressor, causing a conformational change that releases the repressor from the operator, allowing for the expression of the lac genes.
My answer is 3, I am pretty sure I am right, but I would double check to make sure. I am in ninth grade taking biology at PineTree.
The lac operon is found in prokaryotes, specifically in bacteria such as Escherichia coli. It is a regulatory system that controls the expression of genes involved in lactose metabolism. Eukaryotic cells do not typically have operons like the lac operon.
The lac structural genes are expressed most efficiently in the presence of lactose and absence of glucose, as regulated by the lac operon in E. coli. When lactose is present, it binds to the lac repressor protein causing it to release from the lac operator, allowing RNA polymerase to bind and transcribe the structural genes. Glucose repression prevents catabolite repression, ensuring that the lac genes are expressed in the presence of lactose as the preferred carbon source.
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.
A lac repressor turns off the lac genes by binding to the operator
Allolactose is a molecule that binds to the lac repressor protein in E. coli, causing it to detach from the lac operator region in the lac operon. This allows RNA polymerase to bind to the promoter and transcribe the genes necessary for lactose metabolism. Ultimately, this process enables the bacteria to use lactose as an energy source.
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it is by lac operon syastem
The presence of lactose enables RNA polymerase to transcribe the lac genes by inducing a conformational change in the lac repressor protein. This change prevents the lac repressor from binding to the lac operator, allowing RNA polymerase to access the promoter region and initiate transcription of the lac genes.
The E. coli lac Z gene is used as a reporter gene in S. cerevisiae cells because the yeast lacks the lactose metabolism pathway, making it suitable for detecting lac Z expression. In contrast, E. coli naturally metabolizes lactose using the lac Z gene, so it is not ideal for use as a reporter gene in the same species.