Suppose that an operon that exhibited positive control was inducible. Would the regulator gene in this case produce an active or an inactive activator protein? What would most likely turn transcription on? What about an operon with positive control that was repressible? In this case, what would turn transcription off? Explain your reasoning.

Suppose that an operon that exhibited positive control was inducible. Would the regulator gene in this case produce an active or an inactive activator protein? What would most likely turn transcription on? What about an operon with positive control that was repressible? In this case, what would turn transcription off? Explain your reasoning.

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 11TYU

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A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcription
If glucose levels in the cell are high and lactose is available from the environment, what is the status of transcription of the lac operon genes? Explain your answer from both an evolutionary perspective and in terms of negative and positive regulation of the operon?
If you add a co-eepressor to a repressor protein and that allows it to bind the operator is this a inducible, constitutive or repressible operon?
Describe two examples of regulators that acted on transcription at steps after initiation. Of the two examples, one must be from a phage system and the other from a bacterial biosynthetic operon.
The lac operon produces enzymes that allow the bacteria E. coli to metabolize lactose, it is in an inducable operon. When lactose is present, will the repressor protein attach or leave the operon? How would this effect the production of lactose producing enzymes?
You then make a screen to identify potential mutants (shown as * in the diagram) that are able to constitutively activate Up Late operon in the absence of Red Bull and those that are not able to facilitate E. Coli growth even when fed Red Bull. You find that each class of mutations localize separately to two separate regions. For those mutations that prevent growth even when fed Red Bull are all clustered upstream of the core promoter around -50 bp. For those mutations that are able to constitutively activate the operon in the absence of Red Bull are all located between the coding region of sleep and wings. Further analysis of each DNA sequence shows that the sequence upstream of the promoter binds the protein wings and the region between the coding sequence of sleep and wings binds the protein sleep. When the DNA sequence of each is mutated, the ability to bind DNA is lost. Propose a final method of gene regulation of the Up Lateoperon using an updated drawn figure of the Up Late…
Let’s suppose you have isolated a mutant strain of E. coli in which the lac operon is constitutively expressed. In other words, the operon is turned on in the presence or absence of lactose. One possibility is that the mutation may block the transcription of the lacI gene, thereby preventing the synthesis of lac repressor. A second possibility is that the mutation could alter the sequence of the lac operon in a way that prevents the repressor protein from binding to the operator. How would you distinguish between these two possibilities?
The promoter of an operon is the site to which RNA polymerase binds to begin transcription. Certain base changes in the promoter result in a mutant site that RNA polymerase can’t bind. Would you expect mutations in the promoter that prevents binding of RNA to act in trans on another copy of the operon on a plasmid or only in cis on the copy immediately adjacent to the mutated site?
If an abnormal repressor protein could still bind allolactose but the binding of allolactose did not alter the conformation of the repressor protein, how would the expression of the lac operon be affected?
In the presence of lactose and the promoter sequence was mutated such that the RNA polymerase can no longer bind, the structural genes will:[ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the absence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"] In the presence of lactose and the lacI repressor gene is mutated such that the repressor protein product can no longer bind to the operator, the structural genes will: [ Select ] ["No longer be expressed", "Be constantly expressed", "Be deleted from the operon"]
In the lac operon (below), how will expression of the genes lacZ and lacy be effect by a mutation in the repressor protein (encoded by lach) that prevents it from binding the operator sequence (lacO) in the absence of lactose? Explain the answer
Consider the following scenario: A bacteria cell is surrounded by lactose, but there is no glucose readily available. Will the lac operon be active (on) or inactive (off)? Explain in your own words. If it is active, describe the levels (low or high) of transcription, and any positive regulators assisting with this. If it is inactive, describe the negative regulators assisting with this, and how the operon could be turned on. Question 48 options: