What is the effect of tryptophan and allolactose binding on the function of the trpR protein and the lacI protein respectively?Group of answer choicesThe trpR protein binds the DNA when it is NOT bound to tryptophan, and the lacI protein binds the DNA when it is NOT bound to allolactose.The trpR protein binds the DNA when it is bound to tryptophan, and the lacI protein binds the DNA when it is bound to allolactose. The trpR protein does NOT bind the DNA when it is bound to tryptophan, but the lacI protein binds the DNA when it is bound to allolactose.The trpR protein binds the DNA when it is bound to tryptophan, but the lacI protein binds the DNA when it is NOT bound to allolactose.

What is the expression of the trp operon in the presence of tryptophan?Group of answer choicesThe trpR protein binds so the trp operon is expressedThe trpR protein does not bind, so the trp operon is expressed.The trpR protein binds so the trp operon is not expressedThe trpR protein does not bind, so there is no expression from the trp operon

How does the lac repressor inhibit transcription?Group of answer choicesIt binds to the RNA polymerase and prevents its association to DNA.It binds to DNA and prevents the RNA polymerase from unwinding and transcribing the DNA.It binds to the RNA molecule, preventing ribosomes from binding.All of the aboveNone of the above

The trp repressor proteinGroup of answer choicesShares the same promoter as the structural genesBinds non-specifically to the trp operatorHas an allosteric binding site for tryptophan (the co-repressor)Is the product of an inducible geneIs active in its native conformation

Lactose or its analogues act as positive regulators of Lac operon by:Select one:a. Binding to repressor subunits so that the repressor cannot attached to operator locus.b. Attaching to I gene and preventing its expressionc. Attaching to promoter region and facilitating the biding of RNA polymerased. Increasing the synthesis of catabolic gene activator protein.Clear my choice

The lac operon system, first described by Jacob and Monod, regulates lactose metabolism in . The is composed of a gene encoding a protein that normally keeps this operon in the position. Within the , the repressor binds to the , blocking transcription of structural genes needed for lactose metabolism. When is added to a cell's environment, it binds the repressor freeing the operator segment of the DNA. is now able to bind to the promoter, transcribing all three structural genes needed for lactose catabolism. When lactose again becomes depleted in the cell, the repressor binds to the operator blocking additional synthesis of enzymes from the .