In the lac and trp operons, the repressors are said to be "allosteric molecules" because they undergo a conformational change when they interact with another molecule they stimulate transcription of these operons they repress transcription of their respective operons they can act as a repressor in one operon and an activator in another operon they affect the production of lactose and tryptophan

In the lac and trp operons, the repressors are said to be "allosteric molecules" because they undergo a conformational change when they interact with another molecule they stimulate transcription of these operons they repress transcription of their respective operons they can act as a repressor in one operon and an activator in another operon they affect the production of lactose and tryptophan

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 9TYU: A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous...

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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
The figure at the beginning of this chapter showsthe binding of both a Lac repressor tetramer and aCRP-cAMP complex to the regulatory region of thelac operon.a. What is the key feature of a regulatory protein suchas the Lac repressor or CRP that allows it to regulate specifically the genes or operons it is supposedto control?b. On the figure, show the positions of the followingcomponents: (i) A Lac repressor monomer; (ii) a Lacrepressor dimer; (iii) all four DNA binding domains ofthe Lac repressor tetramer; (iv) a single helix-turnhelix motif; (v) the o1 part and either the o2 or o3 partsof the lac operator (assume the operon would be transcribed from right to left on the figure); (vi) themultimerization domains of the four Lac repressormonomers; (vii) an inducer-interacting domain; (viii)the CRP-cAMP complex; and (ix) a DNA loop.c. What is the physical basis for the formation of theDNA loop shown in the figure?d. On the figure, show the position of two axes ofsymmetry in the sequence…
A mutation at the operator prevents the regulator protein from bindingWhat effect will this mutation have in the following types of operons? a. Regulator protein is a repressor of a repressible operon. b. Regulator protein is a repressor of an inducible operon.
Assuming that the level of glucose is low, a mutation in the repressor associated with the lac operon of E. coli which prevents binding of the repressor to lactose should result in_____ Constitutive expression of the lac operon genes ito sagot ko Lack of expression or reduced expression of the lac operon genes under all circumstances Expression of the genes only when lactose is present Expression of the genes only when lactose is absent
The promoter of an operon is the site to which RNApolymerase binds to begin transcription. Certain basechanges in the promoter result in a mutant site towhich RNA polymerase cannot bind. Would you expect mutations in the promoter that prevent binding ofRNA polymerase to act in trans on another copy ofthe operon on a plasmid in the cell, or only in cis onthe copy immediately adjacent to the mutated site?
In the lac and trp operons, the repressors are said to be “allosteric molecules” because ___________________________. they undergo a conformational change when they interact with another molecule they stimulate transcription of these operons they affect the production of lactose and tryptophan they can act as a repressor in one operon and an activator in another operon they repress transcription of their respective operons
Which of the following condition(s) is optimal for expression of the lac operon? I. low glucose and formation of CAP-cAMP complex II. high glucose resulting in no cAMP III. no lactose present and a functional repressor IV. presence of lactose binding to a functional repressor
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…
Describe the main functional differences between the TRP and the Lac operons. Main functional differences DO NOT refer to the fact that one operon involves TRP and the other involves Lac. They also don’t include that there are different genes found in the TRP operon compared to the Lac operon or that the repressor in the Lac operon is called Lac l. Also DO NOT simply list how both operons work to answer this question.
Which of the following statements about the trp operon is false? If a mutation in region 2 prevents the formation of the 2 + 3 loop in the 5’UTR transcription levels will increase. The trp operon is an example of negative repressible operon. Formation of the anti-terminator in the 5’UTR of the trp operon occurs when trp levels are low. In the presence of high trp-tRNA, the genes of the trp operon are not expressed. The role of trp is to bind to the repressor protein and activate it.
. In an effort to determine the location of an operator sitefor a negatively regulated gene, you have made a seriesof deletions within the regulatory region. The extent ofeach deletion is shown by the line underneath the sequence, and the resulting expression from the operon(i = inducible; c = constitutive; − = no expression) isalso indicated.... GGAT C T T AGCCGGCTAACATGATAAATATAA......C C T AGAATCGGCCGA TTGTA C T A TTT ATAT T ...1 i2 –3 c4 –5 ca. What can you conclude from these data about thelocation of the operator site?b. Why do you think deletions 2 and 4 show no expression of the gene?