Genetics: From Genes to Genomes, 5th edition
5th Edition
ISBN: 9780073525310
Author: Leland H. Hartwell, Michael L. Goldberg, Janice A. Fischer, Leroy Hood, Charles F. Aquadro
Publisher: McGraw-Hill Education
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Chapter 15, Problem 8P
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.
| a. Is the DNA-binding protein a positive or negative regulator of gene expression? | ||
b. 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?
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| c. What results do you predict for the two strains (i and ii) if reg1 encodes the regulatory protein and reg2 is the regulatory site? |
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You have isolated two different mutants (reg1 andreg2) causing constitutive expression of the emu operon (emu1 emu2). One mutant contains a defect in aDNA-binding site, and the other has a loss-of-functiondefect in the gene encoding a protein that binds tothe site.a. Is the DNA-binding protein a positive or negativeregulator of gene expression?b. To determine which mutant has a defect in the siteand 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 Emu1and Emu2 proteins, what results do you predict forthe two strains (i and ii; see descriptions below) ifreg2 encodes the regulatory protein and reg1 is theregulatory site?i. F′ (reg1−reg2+emu1−emu2+)/reg1+reg2+emu1+emu2−ii. F′ (reg1+reg2−emu1−emu2+)/reg1+reg2+emu1+emu2−c. What results do you predict for the two strains(i and ii) if reg1 encodes the regulatory proteinand reg2 is the regulatory site?
For the trp operon, determine whether genes will be expressed (on) or silenced (off) given the following:
a. Tryptophan levels are high.
b. The trp repressor can no longer bind tryptophan.
You have isolated different mutants (reg1 and reg2) causing constitutive expression of the emu operon (which has genes emu1 and 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?
Chapter 15 Solutions
Genetics: From Genes to Genomes, 5th edition
Ch. 15 - For each of the terms in the left column, choose...Ch. 15 - The following statement occurs early in this...Ch. 15 - One of the main lessons of this chapter is that...Ch. 15 - All mutations that abolish function of the Rho...Ch. 15 - The promoter of an operon is the site to which RNA...Ch. 15 - You are studying an operon containing three genes...Ch. 15 - Prob. 7PCh. 15 - You have isolated two different mutants reg1 and...Ch. 15 - Bacteriophage , after infecting a cell, can...Ch. 15 - Mutants were isolated in which the constitutive...
Ch. 15 - For each of the E. coli strains containing the lac...Ch. 15 - For each of the growth conditions listed, what...Ch. 15 - For each of the following mutant E. coli strains,...Ch. 15 - Maltose utilization in E. coli requires the...Ch. 15 - Seven E. coli mutants were isolated. The activity...Ch. 15 - Prob. 16PCh. 15 - Six strains of E.coli mutants 16 that had one of...Ch. 15 - a. The original constitutive operator mutations in...Ch. 15 - Prob. 19PCh. 15 - Figure 15.16 on p. 525 shows that in the lac...Ch. 15 - Why is the trp attenuation mechanism unique to...Ch. 15 - a. How many ribosomes are required at a minimum...Ch. 15 - The following is a sequence of the leader region...Ch. 15 - For each of the E. coli strains that follow,...Ch. 15 - One mechanism by which antisense RNAs act as...Ch. 15 - For each element in the list that follows,...Ch. 15 - Great variation exists in the mechanisms by which...Ch. 15 - Many genes whose expression is turned on by DNA...Ch. 15 - Prob. 29PCh. 15 - The E.coli MalT protein is a positive regulator of...Ch. 15 - Prob. 31PCh. 15 - To find genes that are turned on or off in...Ch. 15 - Prob. 33PCh. 15 - Prob. 34PCh. 15 - Prob. 35PCh. 15 - The researchers who investigated bioluminescence...Ch. 15 - Prob. 37PCh. 15 - Quorum sensing controls the expression of...
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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
- You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan. Using your knowledge of operons and their regulation a.Which operons would be functional under these conditions? b.What repressors would be made? (NOTE: name the repressors using their gene names) c.Which repressor(s) would be made in the inactive form? d.Which repressor(s) would be made in the active form? e.Which repressor(s) under these conditions can bind the operator sequence? f.Which repressor(s)under these conditions cannot bind the operator sequence?arrow_forwardYou have isolated different mutants (reg1 and reg2) causing constitutive expression of the emu operon (which has genes emu1 and 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 Say you don’t know which mutant has a defect in the site and which one has a mutation in the binding protein. To figure it out, you construct the two partial diploid strains (i and ii below), and you then assay the levels of the Emu1 and Emu2 proteins in these two strains. F’ (reg1- reg2+ emu1- emu2+) / reg1+ reg2+ emu1+ emu2- F’ (reg1+ reg2- emu1- emu2+) / reg1+ reg2+ emu1+ emu2- What proteins do you predict will be expressed for strains i and ii if reg2 encodes the regulatory protein and reg1 is the regulatory site?arrow_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_forward
- There is Hyaluronic acid synthesis occuring in Group X Strep and it is controlled by an operon with 3 genes, called hasXYZ. Based on the 3-line diagram model, a. How many ribosome binding sites are there for the protein? b. How many promoters are there for the genes? c. How many start codons are there for the protein? d. How many RNA Polymerase binding locations are there for the genes? e. How many proteins will be fully functional? f. How many mRNA strands are made?arrow_forwardHelp me pleasearrow_forwardThe lactose operon in E. coli comprises two structural genes and three regulatory components.a.State the name of each structural gene and describe its function: b.) State the name of each regulatory component and describe its functionarrow_forward
- On its chromosome, an E. coli cell has a genotype of lacI− lacZ+ lacY+ lacA+. It has an F′ factor with a genotype of lacI+ lacZ+ lacY+ lacA+. What is the expected level of expression of the lac operon genes (lacZ+ lacY+ lacA+) in the absence of lactose?a. Both lac operons will be expressed.b. Neither lac operon will be expressed.c. Only the chromosomal lac operon will be expressed.d. Only the lac operon on the F′ factor will be expressed.arrow_forwardIf a wild-type (normal, NOTmutated) E. coli strain is grown in a medium: a. without lactose or glucose, how many proteins (and which ones) are bound to the lac operon? b. Without lactose, but with glucose, how many proteins (and which ones) are bound to the lac operon??arrow_forwardIf a wild-type (normal, NOTmutated) E. coli strain is grown in a medium: a. without lactose or glucose, how many proteins (and which ones) are bound to the lac operon? b. Without lactose, but with glucose, how many proteins (and which ones) are bound to the lac operon??- lac repressorarrow_forward
- When iron is scarce, some bacteria can stop synthesis of all enzymes that require iron (Fe3+), such as superoxide dismutase (SOD). Which of the following accurately describes a mechanism for this regulation? Mark all that apply. A. Regulation occurs by an inducible operon B. When absent, the lack of iron causes the repressor to deactivate and block the promoter region for these genes C. Regulation occurs by a repressible operon D. When present, iron binds and activates the repressor proteinarrow_forwardE. coli has five genes that code for enzymes that make tryptophan. These genes are regulated by a single promoter and transcribed as one long gene. The presence of tryptophan shut down the production of tryptophan by the cell by binding to the repressor. This changes the repressors shape allowing it to bind to DNA operator, blocking RNA polymerase and cutting off the production of tryptophan. a. Describe what would happen to the operon if some of the cells had a mutation on the repressor, not allowing it to bind with tryptophan. The repressor is described as an allosteric protein. What does this mean? b. Does the tryptophan model demonstrate an inducible or repressible operon? What is your evidence?*arrow_forwardMutations in bacterial promoters may increase or decrease the rate of gene transcription. Promoter mutations that increase the transcription rate are termed up-promoter mutations, and those that decrease the transcription rate are termed down-promoter mutations. As shown , the sequence of the −10 site of the promoter for the lac operon is TATGTT. Would you expect the following mutations to be up-promoter or down-promoter mutations? A. TATGTT to TATATT B. TATGTT to TTTGTT C. TATGTT to TATGATarrow_forward
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