For the lac operon, when glucose is absent and lactose is present ___________ None of the options cAMP-CAP is bound to the operator and the repressor is not bound to the promoter cAMP-CAP is not bound to the promoter and the repressor is bound to the operator cAMP-CAP is bound to the promoter and the repressor is not bound to the operator

For the lac operon, when glucose is absent and lactose is present ___________ None of the options cAMP-CAP is bound to the operator and the repressor is not bound to the promoter cAMP-CAP is not bound to the promoter and the repressor is bound to the operator cAMP-CAP is bound to the promoter and the repressor is not bound to the operator

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter16: Regulation Of Gene Expression

Section: Chapter Questions

Problem 2TYK: For the E. coli lac operon, when lactose is present: a. and glucose is absent, cAMP binds and...

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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
INTERPRET DATA Develop a simple hypothesis that would explain the behavior of each of the following types of mutants in E. coli. Mutant a: The map position of this mutation is in the trp operon. The mutant cells are constitutive; that is, they produce all the enzymes coded for by the trp operon, even if large amounts of tryptophan are present in the growth medium. Mutant b: The map position of this mutation is in the trp operon. The mutant cells do not produce any enzymes coded for by the trp operon under any conditions. Mutant c: The map position of this mutation is some distance from the trp operon. The mutant cells are constitutive; that is, they produce all the enzymes coded for by the trp operon, even if the growth medium contains large amounts of tryptophan.
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.
In the lac operon (above), what happens when glucose levels are low, but lactose levels increase? the repressor protein is detached from the operator, and transcription is not initiated the repressor protein is attached to the operator, and transcription is not initiated the repressor protein is detached from the operator, and transcription is initiated the repressor protein is attached to the operator, and transcription is initiated. Check all of the above occur at equal rates when glucose levels are low but lactose levels are high
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+
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) I+ OC Z+ I+ O+ Z+ (Lactose present) I- O+ Z+
To study the lac operon, you engineer a strain of E coli to have a lac operon in which the lac Z gene is replaced by the gene for green fluorescent protein (GFP). Expression of GFP generates a green color in the cells that can be easily quantitated with a fluorescence microscope. You test the activity of the operon in the absence of the inducer IPTG, the presence of the inducer IPTG and the presence of an antibiotic the completely inhibits RNA polymerase (i.e. no gene expression). You then use this system to test the effects of various mutation on the activity of the operon. Match the following mutations with the activity (A, B or C) you would expect to observe with the mutation. All experiments are done in the presence of IPTG unless otherwise stated.
In the lac operon system, lactose is considered the ___________, and when the gene lacI is mutated such that the protein it produces cannot bind to lactose (IS mutation), the lac operon is ________. Group of answer choices repressor; never expressed activator; constitutively expressed inducer; never expressed inducer; constitutively expressed structural gene; never expressed
Maltose utilization in E. coli requires the proteins encoded by genes in three different operons. One operonincludes the genes malE, malF, and malG; the secondincludes malK and lamB; and the genes in the thirdoperon are malP and malQ. The MalT protein is apositive regulator that controls the expression of allthree operons; expression of the malT gene itself iscatabolite sensitive.a. What phenotype would you expect to result from aloss-of-function mutation in the malT gene?b. Do you expect the three maltose operons to containbinding sites for CRP (cAMP receptor protein)?Why or why not?In order to infect E. coli, bacteriophage λ binds to themaltose transport protein LamB (also known as the λreceptor protein) that is found in the outer membraneof the bacterial cell. The synthesis of LamB is induced by maltose in the medium via expression of theMalT protein, as described above
Maltose utilization in E. coli requires the proteins encoded by genes in three different operons. One operonincludes the genes malE, malF, and malG; the secondincludes malK and lamB; and the genes in the thirdoperon are malP and malQ. The MalT protein is apositive regulator that controls the expression of allthree operons; expression of the malT gene itself iscatabolite sensitive.a. What phenotype would you expect to result from aloss-of-function mutation in the malT gene?b. Do you expect the three maltose operons to containbinding sites for CRP (cAMP receptor protein)?Why or why not?In order to infect E. coli, bacteriophage λ binds to themaltose transport protein LamB (also known as the λreceptor protein) that is found in the outer membraneof the bacterial cell. The synthesis of LamB is induced by maltose in the medium via expression of theMalT protein, as described above.c. List the culture conditions under which wild-typeE. coli cells would be sensitive to infection bybacteriophage…
A mutation in the repressor LacI causes it to lose the ability to bind its effector, allolactose. What will be the effect of this mutation in the presence of allolactose (assume glucose is absent)? a) LacI cannot bind to the lac operator (lacO) and transcription of the lac operon is blockedb) LacI is permanently bound to the lac operator (lacO) and transcription of the lac operon is blocked c) LacI cannot bind to the lac operator (lacO) and transcription of the lac operon increasesd) LacI is permanently bound to the lac operator (lacO) and transcription of the lac operon increases
Given the Table below concerning the lac operon, match the letter with what would be occurring for each scenario. Repressor is bound to the operator, cAMP complex is bound and transcription is prevented. Allolactose is bound to the repressor, cAMP complex is bound, and transcription is prevalent. Allolactose is bound to the repressor, cAMP complex is not assembled, and transcription is slow Repressor is bound to the operator, cAMP complex is not assembled, and transcription is prevented.