Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 16, Problem 17P
Maltose utilization in E. coli requires the proteins encoded by genes in three different operons. One operon includes the genes malE, malF, and malG; the second includes malK and lamB; and the genes in the third operon are malP and malQ. The MalT protein is a positive regulator that controls the expression of all three operons; expression of the malT gene itself is catabolite sensitive.
| a. What |
| b. Do you expect the three maltose operons to contain binding sites for CRP (cAMP receptor protein)? Why or why not? In order to infect E. coli, bacteriophage λ binds to the maltose transport protein LamB (also known as the λ receptor protein) that is found in the outer membrane of the bacterial cell. The synthesis of LamB is induced by maltose in the medium via expression of the MalT protein, as described above. |
| c. List the culture conditions under which wild-type E. coli cells would be sensitive to infection by bacteriophage λ. |
| d. E. coli cells that are resistant to infection by bacteriophage λ have been isolated. List the types of mutations in the maltose regulon (the set of all genes regulated by maltose) that λ-resistant mutants could contain. |
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Students have asked these similar questions
You have isolated two different mutants (reg1 and reg2) causing constitutive expression of the emu operon (emu1 emu2). One mutant contains a defect in a DNA-binding site, and the other has a loss-of-function defect in the gene encoding a protein that binds to the site.
Is the DNA-binding protein a positive or negative regulator of gene expression? Explain.
To determine which mutant has a defect in the site and which one has a mutation in the binding protein, you decide to do an analysis using F′ plasmids. Assuming you can assay levels of the Emu1 and Emu2 proteins, what results do you predict for the two strains (i and ii; see descriptions below) if reg2 encodes the regulatory protein and reg1 is the regulatory site? Explain.
F′ (reg1− reg2+ emu1− emu2+)/reg1+ reg2+ emu1+ emu2−
F′ (reg1+ reg2− emu1− emu2+)/reg1+ reg2+ emu1+ emu2−
Under what conditions would you expect to see high levels of expression of the structural genes in the lac operon?
Group of answer choices
Lactose is absent and glucose is absent
Lactose is absent and glucose is present
Lactose is present and glucose is present
None of these
Lactose is present and glucose is absent
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
Chapter 16 Solutions
Genetics: From Genes to Genomes
Ch. 16 - For each of the terms in the left column, choose...Ch. 16 - The following statement occurs early in this...Ch. 16 - One of the main lessons of this chapter is that...Ch. 16 - All mutations that abolish function of the Rho...Ch. 16 - The figure at the beginning of this chapter shows...Ch. 16 - The promoter of an operon is the site to which RNA...Ch. 16 - You are studying an operon containing three genes...Ch. 16 - You have isolated a protein that binds to DNA in...Ch. 16 - You have isolated two different mutants reg1 and...Ch. 16 - Bacteriophage , after infecting a cell, can...
Ch. 16 - Mutants were isolated in which the constitutive...Ch. 16 - Suppose you have six strains of E. coli. One is...Ch. 16 - The previous problem raises some interesting...Ch. 16 - For each of the E. coli strains containing the lac...Ch. 16 - For each of the following growth conditions, what...Ch. 16 - For each of the following mutant E. coli strains,...Ch. 16 - Maltose utilization in E. coli requires the...Ch. 16 - Seven E. coli mutants were isolated. The activity...Ch. 16 - Cells containing missense mutations in the crp...Ch. 16 - Six strains of E.coli mutants 16 that had one of...Ch. 16 - a. The original constitutive operator mutations in...Ch. 16 - In an effort to determine the location of an...Ch. 16 - Prob. 23PCh. 16 - The footprinting experiment described in Fig....Ch. 16 - Why is the trp attenuation mechanism unique to...Ch. 16 - a. How many ribosomes are required at a minimum...Ch. 16 - The following is a sequence of the leader region...Ch. 16 - For each of the E. coli strains that follow,...Ch. 16 - Prob. 29PCh. 16 - For each element in the list that follows,...Ch. 16 - Among the structurally simplest riboswitches are...Ch. 16 - Great variation exists in the mechanisms by which...Ch. 16 - Many genes whose expression is turned on by DNA...Ch. 16 - In 2005, Frederick Blattner and his colleagues...Ch. 16 - The E.coli MalT protein is a positive regulator of...Ch. 16 - Prob. 36PCh. 16 - Prob. 37PCh. 16 - Prob. 38PCh. 16 - Prob. 39PCh. 16 - Prob. 40PCh. 16 - Prob. 41PCh. 16 - The researchers who investigated bioluminescence...Ch. 16 - Prob. 43PCh. 16 - Quorum sensing controls the expression of...Ch. 16 - Scientists are currently screening a chemical...
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- . In the lac operon of E. coli, if glucose levels increase while lactose levels decrease, what will happen in the regulation of genes controlling the enzymes needed to catabolize lactose? the lac operon will be activated due to cAMP-assisted CAP binding to a site near the promoter the lac operon will be activated due to CAP detachment from a site near the promoter the lac operon will be repressed due to cAMP-assisted CAP binding to a site near the promoter the lac operon will be repressed due to CAP detachment from a site near the promoter all of the abovearrow_forwardThe lac operon consists of regulatory regions such as the promoter as well as the structural genes lacZ, lacY, and lacA, which code for proteins involved in lactose metabolism. What would be the outcome of a mutation in lacA?arrow_forwardA strain of E. coli has the genotypes shown below at the lac operon, where I = regulator gene, P = promoter, O = operator, Z = βgalactosidase gene, and Y = permease gene. The superscript+ indicates a wild-type allele,c indicates a constitutive mutation, and− indicates a defective mutation. For each genotype, indicate whether the enzyme will be synthesized or not synthesized when lactose is present or absent by placing a + for synthesis occurring and a − for synthesis not occurring in the appropriate blank. Explain your reasoning for each answer.arrow_forward
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