What would happen if there was a mutation in the regulatory gene for the lac operon so that the regulatory protein did not bind to lactose sugar?
An “up” mutation would make the lac operon no longer dependent on the positive regulation by the cAMP‑CAP complex (when the operon is induced). A “down” mutation would not allow expression even in the de‑repressed state (presence of inducer) and hence would show a non‑inducible phenotype.
What would happen if a mutation altered the DNA sequence of the lac operator so that the lac repressor Cannot bind?
What would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator? In the presence of lactose, the lac operon will not be transcribed. In the absence of lactose, the lac operon will be transcribed.
Which of the following results would occur if the repressor of an inducible operon were mutated so that it could not bind the inducer?
The lac operon will function normally. Which of the following results would occur if the repressor of an inducible operon were mutated so that it could not bind the operator? The lac operon would be transcribed continuously.
What might be the result of such a mutation within the Lac i regulatory region of the lac operon?
What might be the result of such a mutation within the LAC regulatory region of the LAC operon (model 1)? The monomers won’t break up. Describe the 4 combinations of active or inactive regulatory proteins that could be present at any time in the cell.
When both glucose and lactose are absent?
Glucose absent, lactose present: Strong transcription of the lac operon occurs. The lac repressor is released from the operator because the inducer (allolactose) is present. cAMP levels are high because glucose is absent, so CAP is active and bound to the DNA.
What is the inducer for the lactose operon?
What is the meaning of inducer?
: one that induces especially : a substance that is capable of activating the transcription of a gene by combining with and inactivating a genetic repressor.
Why is lactose an inducer?
Lactose acts as an inducer in Lac operon by binding to the repressor protein, the repressor protein is produced by the inhibitory gene (LacI) present upstream to the operon gene. So a negligible amount of other proteins from the Z,Y and A genes are produced.
How specifically does lactose allow for an increase in transcription?
How specifically does lactose allow for an increase in transcription? Lactose binds to the repressor protein, preventing it from binding to the operon, allowing transcription to occur. Lactose binds to the repressor protein, causing it to bind more rapidly to the operon, allowing transcription to occur.
What two conditions must be satisfied for the lac operon to be on?
However, for the lac operon to be activated, two conditions must be met. First, the level of glucose must be very low or non-existent. Second, lactose must be present. If glucose is absent, then CAP can bind to the operator sequence to activate transcription.
Is cAMP an activator?
cAMP receptor protein (CRP; also known as catabolite activator protein, CAP) is a regulatory protein in bacteria. CRP protein binds cAMP, which causes a conformational change that allows CRP to bind tightly to a specific DNA site in the promoters of the genes it controls.
Is it possible to get any transcription of the lac operon in the absence of lactose?
Is it possible to get any transcription of the lac operon in the absence of lactose? Why or why not? Yes, because although the repressor protein keeps transcription at a very low basal level, some transcripts will be produced and translated.
What is the regulatory gene in lac operon?
However, the lacI gene (regulatory gene for lac operon) produces a protein that blocks RNAP from binding to the operator of the operon. This protein can only be removed when allolactose binds to it, and inactivates it. The protein that is formed by the lacI gene is known as the lac repressor.