E. coli are grown on a medium containing lactose. Once glucose is added to the medium, the bacteria stop fermenting lactose. Which of the following BEST explains the observed effect? A. Cellular levels of cAMP are low B.Glucose is bound to the promoter C. Repressor protein is bound to the operator D. Repressor protein is bound to the promoter

E. coli are grown on a medium containing lactose. Once glucose is added to the medium, the bacteria stop fermenting lactose. Which of the following BEST explains the observed effect? A. Cellular levels of cAMP are low B.Glucose is bound to the promoter C. Repressor protein is bound to the operator D. Repressor protein is bound to the promoter

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Description: E. coli are grown on a medium containing lactose. Once glucose is added to the medium, the bacteria stop fermenting lactose. Which of the following BEST explains the observed effect?A. Cellular levels of cAMP are lowB.Glucose is bound to the promoter

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 10TYU: Which of the following is an example of positive control? (a) transcription occurs when a repressor...

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E. coli has five genes that code for enzymes that make tryptophan. These genes are regulated by a single promoter and transcribed as one long gene. The presence of tryptophan shut down the production of tryptophan by the cell by binding to the repressor. This changes the repressors shape allowing it to bind to DNA operator, blocking RNA polymerase and cutting off the production of tryptophan. a. Describe what woud happen to the operon if some of the cells had a mutation on the repressor, not allowing it to bind with tryptophan. The repressor is described as an allosteric protein. What does this mean? b. Does the tryptophan model demonstrate an inducible or repressible operon? What is your evidence? *
E. coli has five genes that code for enzymes that make tryptophan. These genes are regulated by a single promoter and transcribed as one long gene. The presence of tryptophan shut down the production of tryptophan by the cell by binding to the repressor. This changes the repressors shape allowing it to bind to DNA operator, blocking RNA polymerase and cutting off the production of tryptophan. a. Describe what would happen to the operon if some of the cells had a mutation on the repressor, not allowing it to bind with tryptophan. The repressor is described as an allosteric protein. What does this mean? b. Does the tryptophan model demonstrate an inducible or repressible operon? What is your evidence?*
The E. coli lacZYA región will be transcribed at a rate greater than the low basal rate if: A. glucose and lactose are both present in the growth medium, but there's a defect in the cells ability to synthesize cAMP B. there is a defect in binding of the inducer to the product of the lacl gene C. glucose and lactose are both readily available in the growth medium D. the operator has mutated so it can no longer bind repressor E. none of the above
You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan. Using your knowledge of operons and their regulation a.Which operons would be functional under these conditions? b.What repressors would be made? (NOTE: name the repressors using their gene names) c.Which repressor(s) would be made in the inactive form? d.Which repressor(s) would be made in the active form? e.Which repressor(s) under these conditions can bind the operator sequence? f.Which repressor(s)under these conditions cannot bind the operator sequence?
A mutation in the operator region of the trp operon can prevent the trp repressor from binding to this operator. When these mutant cells are placed in a solution containing chicken broth, which of the following happens? a. Tryptophan would bind to the repressor. b. The Repressor would bind to the operator irrespective of the presence of amino acids in the environment. c. The transcription of the trip operon would be inhibited. d. The transcription of the repressor protein is inhibited
Define the following terms: a. promoter b. consensus sequence c. operon d. chromatin-remodeling complex e. general transcription factors
Escherichia coli is grown in the presence of 20 mg of glucose and 20mg of lactose as carbon sources. The major carbon source is consumed by Escherichia at a rate of 10 mg/hour. Which of the following best describes the actions of RNA polymerase, the promoter and the sugar being used after 3 hours? O The sugar binds to the repressor, inactivating it, allowing RNA polymerase to bind to the operator. O RNA polymerase binds to the promoter and the sugar binds to the operator. O The sugar binds to the repressor, inactivating it, and allows RNA polymerase to bind to the promoter. O The sugar binds to RNA polymerase and the repressor binds to a structural gene. Question 41 A Moving to the next question prevents changes to this answer. 61
Study the depiction of the lac operon in Figure 11.2. Normally, the genes are turned off when lactose is not present. Lactose activates the genes, which code for enzymes that enable the cell to use lactose. Mutations can alter the function of this operon. Predict how the following mutations would affect the function of the operon in the presence and absence of lactose: a. mutation of regulatory gene; repressor will not bind to lactose b. mutation of operator; repressor will not bind to operator c. mutation of regulatory gene; repressor will not bind to operator d. mutation of promoter; RNA polymerase will not attach to promoter
You are studying a new gene that is expressed within the adipose tissue of humans during the development of diabetes. Specifically, you want to learn why gene expression levels are very high in those people who develop diabetes. What DNA sequence would you concentrate on? Group of answer choices A specific response elements B the TATA box C enhancer sequences D promoter proximal elements E metal response elements
. In the tryptophan operon of E. coli, what happens when tryptophan levels get too high? tryptophan is removed from its co-repressor, causing it to detach from the operator tryptophan is removed from its co-repressor, causing it to attach to the operator tryptophan is bound to its co-repressor, causing it to detach from the operator tryptophan is bound to its co-repressor, causing it to attach to the operator all of the above occur at equal rates when tryptophan levels get too high
In the above E. coli cell, with high glucose and low lactose levels, what happens at the operator? low lactose causes activation of a repressor protein, allowing it to detach from the operator low lactose causes inactivation of a repressor protein, allowing it to detach from the operator low lactose causes activation of a repressor protein, allowing it to bind to the operator low lactose causes inactivation of a repressor protein, allowing it to bind to the operator all of the above
When iron is scarce, some bacteria can stop synthesis of all enzymes that require iron (Fe3+), such as superoxide dismutase (SOD). Which of the following accurately describes a mechanism for this regulation? Mark all that apply. A. Regulation occurs by an inducible operon B. When absent, the lack of iron causes the repressor to deactivate and block the promoter region for these genes C. Regulation occurs by a repressible operon D. When present, iron binds and activates the repressor protein