One way that regulation is often studied is by examining the effects of mute ons. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant (the operon is always on)? a mutation in CAP that prevents the binding of CAMP a mutation in one of the structural genes that prevents the transport of lactose into the cell a mutation that disables the promoter for the operon a mutation that disables the repressor

One way that regulation is often studied is by examining the effects of mute ons. For example, mutations within the parts of the lac operon have been well studied. Which of these mutants would be considered a constitutive mutant (the operon is always on)? a mutation in CAP that prevents the binding of CAMP a mutation in one of the structural genes that prevents the transport of lactose into the cell a mutation that disables the promoter for the operon a mutation that disables the repressor

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Description: One way that regulation is often studied is by examining the effects of mutations. For example, mutations within the parts ofthe lac operon have been well studied. Which of these mutants would be considered a constitutive mutant (the operon isalways

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 13TYU: INTERPRET DATA Develop a simple hypothesis that would explain the behavior of each of the following...

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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.
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
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
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.
Mutations in the genes of the lac operon might affect the regulation of β-galactosidase synthesis. For each mutation listed below, indicating whether β-galactosidase would be regulated normally, always ON or always OFF. Mutation in operator site prevents repressor binding Mutation in lacIgene prevents repressor from binding operator Mutation in lacIgene prevents repressor from binding allolactose Nonsense mutation in lacZgenere
Mutations in the genes of the lac operon might affect the regulation of β-galactosidase synthesis. For each mutation listed below, indicating whether β-galactosidase would be regulated normally, always ON or always OFF. a. Mutation in operator site prevents repressor binding b. Mutation in lacIgene prevents repressor from binding operator c. Mutation in lacIgene prevents repressor from binding allolactose d. Nonsense mutation in lacZgenere
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…
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.
The activator (V protein) that is present in the bacterial cell is normally phosphorylated, but only binds to the A site in the operon when it is not phosphorylated. What operon-independent mechanism can regulate the binding of (and also ultimately regulates the removal of) protein V to the A site? Describe this binding/removal mechanism in detail – useappropriateterminologythatwasdiscussedinlecture. Aspartofyouransweraboutthisactivatorproteinbindingto (and then detaching from) the A site of the operon, be sure to address what are the results of this type of control in terms of function of the operon.
A mutation that inactivates transcription and translation from the regulatory gene of an inducible operon could result in: Group of answer choices A inactivation of RNA polymerase. B irreversible binding of the repressor to the operator. C three of these choices are correct D inhibition of transcription of the structural genes within the operon. E two of these choices are correct F transcription of the structural genes within that operon.
Imagine that a new strain of E. coli is discovered, and it contains the following novel genetic region including the lacI gene and the lac operon: *see image* Upstream of the promoter associated with the lac operon, there is a new operator element "Oν" (O-"nu"). This new operator has high sequence homology to O1, the DNA element that is bound with the highest affinity by the lac repressor. What would be the impact of this new genetic element regarding behavior of the operonin the absence (vs. the presence) of lactose and allolactose? Answer in terms of the protein levels of the lac repressor, as well as the proteins encoded by the genes lacZ/Y/A in the downstream region of the operon. Remember that proteins, once expressed/generated, will not persist forever, and that they have a natural lifetime (ending when they are degraded by the cell).
. 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?