Biology: The Dynamic Science (MindTap Course List)
4th Edition
ISBN: 9781305389892
Author: Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher: Cengage Learning
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Textbook Question
Chapter 16, Problem 2TYK
For the E. coli lac operon, when lactose is present:
a. and glucose is absent, cAMP binds and activates catabolicactivator protein (CAP).
b. and glucose is absent, the level of cAMP decreases.
c. activated CAP binds the repressor protein to remove it from the operator gene.
d. the cell prefers lactose over glucose.
e. RNA polymerase cannot bind to the promoter.
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If β-galactosidase is expressed when lactose is absent, what does this suggest about the lac operon?
a)
There is a mutation in the repressor protein
b)
There is a mutation in the catabolite activator protein
c)
There is a mutation in the promoter region
d)
There is a mutation in the luxI protein
Gene expression in bacteria is controlled by the operon model.
a) Why is the operon model important?
b) Why is the trp operon known as a repressible operon?
What is the role of a substrate that controls a repressible operon?
a.
increase the production of inactive repressor proteins
b.
bind to the repressor protein and activate it
c.
bind to the repressor protein and deactivate it
d.
bind to the promoter region and decrease the affinity of RNA polymerase for the promoter
Chapter 16 Solutions
Biology: The Dynamic Science (MindTap Course List)
Ch. 16.1 - Suppose the lacl gene is mutated so that the Lac...Ch. 16.1 - Answer the equivalent question for the trp operon:...Ch. 16.2 - What is the role of histones in gene expression?...Ch. 16.2 - Prob. 2SBCh. 16.3 - Prob. 1SBCh. 16.3 - Prob. 2SBCh. 16.4 - Prob. 1SBCh. 16.4 - Prob. 2SBCh. 16.5 - Prob. 1SBCh. 16.5 - Prob. 2SB
Ch. 16.5 - Prob. 3SBCh. 16.5 - Prob. 4SBCh. 16 - Prob. 1TYKCh. 16 - For the E. coli lac operon, when lactose is...Ch. 16 - Prob. 3TYKCh. 16 - Prob. 4TYKCh. 16 - Prob. 5TYKCh. 16 - Prob. 6TYKCh. 16 - Prob. 7TYKCh. 16 - Prob. 8TYKCh. 16 - Prob. 9TYKCh. 16 - Prob. 10TYKCh. 16 - Discuss Concepts In a mutant strain of E. coli,...Ch. 16 - Prob. 12TYKCh. 16 - Prob. 13TYKCh. 16 - Prob. 14TYKCh. 16 - Design an experiment using rats as the model...Ch. 16 - Prob. 1ITDCh. 16 - Prob. 2ITDCh. 16 - Prob. 3ITDCh. 16 - Prob. 4ITD
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- In the trp operon, if a mutation occurred in the gene for the repressor so that it could bind to the operator even in the absence of tryptophan____________. a) the inducer cannot bind trpO, so operon gene transcription occurs b) the active repressor cannot bind trpO, so operon gene transcription is attenuated c)the active repressor binds tpO, so operon gene transcription is always repressed d) the repressor binds the corepressor, and operon gene transcription occurs.arrow_forwardIf CAP is bound to the Promoter of the Lac Operon and the repressor protein is not bound to the operator, which of the following is true: a.Glucose Levels are low & Lactose is absent b.Glucose is absent & Lactose is present c.cAMP is low & Lactose is Absent d.Glucose and Lactose are Present e.cAMP is low & Lactose is presentarrow_forwardThe gad operon is controlled by a number of transcription factors that regulate a promoter of approximately 450bp. Which would NOT explain why bacterial promoters are shorter than the typical eukaryotic promoter? a. Bacteria do not have nucleosomes b. Bacteria do not have mediator complex c. Each operon is regulated by only one signal d. All of the above are truearrow_forward
- 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 inhibitedarrow_forwardA mutation occurs in the lac operon operator site such that LacI can no longer bind to the operator site. The effect that this mutation has on the cell is that a. the activity of the lac operon will not be affected. b. the cell can no longer convert lactose to glucose. c. the expression of the lac genes cannot be turned off. d. the expression of the lac genes cannot be turned on.arrow_forwardYou 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?arrow_forward
- Which of the following statements is false?a) A derivative of lactose serves as an inducer of the lac operon.b) Signal transduction provides a mechanism for a cell to sense the conditions of its external environment.c) Quorum sensing allows bacterial cells to sense the density of like cells.d) An example of a two-component regulatory system is the lactoseoperon, which is controlled by a repressor and an activator.e) An ORF is a stretch of DNA that may encode a protein.arrow_forwardThe presence of glucose in the medium will lead to: a) increased cAMP concentrations and reduction of lac operon gene expression b) increased cAMP concentrations and promotion of lac operon gene expression c) reduced cAMP concentrations and reduction of lac operon gene expression d) reduced cAMP concentrations and promotion of lac operon gene expressionarrow_forwardThe lactose operon is likely to be transcribed when _____. A) there is more glucose in the cell than lactose B) there is glucose but no lactose in the cell C) the cAMP level is high and the lactose level is low D) the cyclic AMP and lactose levels are both high within the cellarrow_forward
- In the presence of tryptophan, and a mutation in the allosteric domain that abolishes tryptophan binding______. a) the active repressor cannot bind trp), so operon gene transription is attenuated b) the inactive repressor cannot bind trpO, so operon gene transcription occurs] c) the active repressor binds trpP, so operon gene trasncription is repressed, the inducer cannot bind trpO, so gene transcription occurs d) the repressor binds to the corepressor, and an operon gene transcription occursarrow_forwardHow does the lac operon regulate lactose digestion in bacteria?a. The repressor protein becomes a lactose-digesting enzyme onlywhen lactose is present.b. The repressor protein binds to the lac operon when lactose ispresent, blocking transcription.c. When lactose is present, it binds to the operator region of the lacoperon, activating transcription of the repressor protein gene.d. The repressor protein falls off the lac operon when lactose ispresent, and lactose-digesting genes are expressed.arrow_forwardA researcher engineers a lac operon on a plasmid but inactivates all parts of the lac operator (lacO) and the lac promoter, replacing them with the binding site for the LexA repressor (which acts in SOS response) and a promoter regulated by LexA. The plasmid is introduced into E. coli cells that have a lac operon with an inactive lacZ gene. Under what conditions will these cells produce beta-galactosidase?arrow_forward
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