Campbell Biology:conc.(ll)-w/access
9th Edition
ISBN: 9780134784427
Author: Reece
Publisher: PEARSON
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Chapter 11, Problem 9TYK
Mutations can alter the function of the lac operon (see Module 11.1). 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 cannot 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.
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Students have asked these similar questions
If the above gene is one of the three structural genes of the lac operon that codes for the protein/ enzyme responsible for breaking lactose into two molecules of simple sugars, what triggers the activation of this gene?
a.
Absence of Inhibitory protein
b.
Presence of lactose
c.
Absence of lactose
d.
Presence of Inhibitory protein
e.
Absence of Regulatory protein
Mutations may have an effect on the expression of the lac operon and the trp operon. Would the following mutations have a cis- or transeffect on the expression of the protein-encoding genes in the operon?
A. A mutation in the operator site that prevents lac repressor from binding to it
B. A mutation in the lacI gene that prevents lac repressor from binding to DNA
C. A mutation in the trpL gene that prevents attenuation
a. What is the function of operons in bacterial gene regulation?
b. Describe how a bacterial operon can be regulated by repressible proteins (such as the tryptophan operon). Include in your description both the “on” and “off” states of the operon. Key elements of your diagram should include: Co-repressor, Genes, mRNA, Operator, Operon, Promoter, Repressor, RNA polymerase.
Chapter 11 Solutions
Campbell Biology:conc.(ll)-w/access
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- 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 proteinarrow_forwardA 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_forwardWhat 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 promoterarrow_forward
- Operons involved with the biosynthesis of molecules such as amino acids are most likely to be regulated in which of the following ways? a. The product of the biosynthetic pathway represses transcription. b. The product of the biosynthetic pathway activates transcription. c. A precursor of the biosynthetic pathway represses transcription. d. A precursor of the biosynthetic pathway activates transcription.arrow_forwardIn 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_forwardStudy the illustration of the lac operon below. Normally, the genes are switched off when lactose is not present. Lactose activates the genes, which code for enzymes that allow the cell to use lactose. Mutations can alter the functions of this operon. Predict how the following mutations would affect the function of the operon the absence and presence of lactose. Mutation of regulatory gene; repressor will not bind to lactose. Mutation of operator; repressor will not bind to operator. Mutation of regulatory gene; repressor will not bind to operator. Mutation of promoter; RNAP will not attach to promoter.arrow_forward
- Define the following in the context of operons: a. positive control b. give an example of an operon that is under positive control c. negative control d. give an example of an operon that is under negative control e. repressor f. give an example of a repressor molecule g. activator h. give an example of an activatorarrow_forwardWhich 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_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_forward
- The lac operon of E. coli controls the expression of genes that code for enzymes involved in lactose metabolism. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I - = produces a repressor protein that cannot bind to the operator region IS = produces a repressor protein that cannot be removed from the operator region OC = cannot bind a repressor protein Z - = produces a defective (non-functioning) β-galactosidase enzyme + = wild type Detail the functionality of the lac operon under the following genetic and cellular conditions. You do not need to consider the role of CAP in your analysis. Genes Repressed (yes/no) Constitutive (yes/no) IS O+ Z+ IS OC Z+arrow_forwardThe lac operon of E. coli controls the expression of genes that code for enzymes involved in lactose metabolism. Mutations to various regions of the lac operon have been discovered which affect both the control of gene expression and the function of the gene products. These mutations include: I - = produces a repressor protein that cannot bind to the operator region IS = produces a repressor protein that cannot be removed from the operator region OC = cannot bind a repressor protein Z - = produces a defective (non-functioning) β-galactosidase enzyme + = wild type Detail the functionality of the lac operon under the following genetic and cellular conditions. You do not need to consider the role of CAP in your analysis. Genes Repressed (yes/no) Constitutive (yes/no) I+ OC Z+ I+ O+ Z+ (Lactose present) I- O+ Z+arrow_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_forward
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