Campbell Essential Biology (7th Edition)
7th Edition
ISBN: 9780134765037
Author: Eric J. Simon, Jean L. Dickey, Jane B. Reece
Publisher: PEARSON
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Chapter 11, Problem 16PS
Study the depiction of the lac operon in Figure 112. Normally the genes are turned off when lactose is not present Lactose activates the genes, which code for enzymes that enable the cell to use lactose. Predict how the following mutations would affect the function of the operon in the presence and absence of lactose:
- a. mutation of regulatory gene, repressor will not bind to lactose
- b. mutation of operator; repressor will not bind to operator
- c. mutation of regulatory gene; repressor will not bind to operator
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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
Study the depiction of the lac operon in Figure 11.2. Normally, the genes are turned off when lactose is not present. Lactose activates the genes, which code for enzymes that enable the cell to use lactose. Mutations can alter the function of this operon. Predict how the following mutations would affect the function of the operon in the presence and absence of lactose: a. mutation of regulatory gene; repressor will not bind to lactose b. mutation of operator; repressor will not bind to operator c. mutation of regulatory gene; repressor will not bind to operator d. mutation of promoter; RNA polymerase will not attach to promoter
Define the following in the context of operons:
a. positive control
b. give an example of an operon that is under positive control
c. negative control
d. give an example of an operon that is under negative control
e. repressor
f. give an example of a repressor molecule
g. activator
h. give an example of an activator
Chapter 11 Solutions
Campbell Essential Biology (7th Edition)
Ch. 11 - Your bore cells, muscle cells, and skin cells look...Ch. 11 - A group of prokaryotic genes with related...Ch. 11 - The regulation of gene expression must be more...Ch. 11 - A eukaryotic gene was inserted into the DNA of a...Ch. 11 - How does DNA packing in chromosomes prevent gene...Ch. 11 - What evidence demonstrates that differentiated...Ch. 11 - The most common procedure for cloning an animal is...Ch. 11 - Prob. 8SQCh. 11 - Prob. 9SQCh. 11 - Prob. 10SQ
Ch. 11 - What is the difference between oncogenes and...Ch. 11 - Prob. 12SQCh. 11 - For each statement, identify which major theme is...Ch. 11 - For each statement, identify which major theme is...Ch. 11 - Prob. 15IMTCh. 11 - Study the depiction of the lac operon in Figure...Ch. 11 - The human body has a far greater variety of...Ch. 11 - Because a cat must have both orange and non-orange...Ch. 11 - Design a DNA microarray experiment that measures...Ch. 11 - Interpreting Data Review Figure 11.22 We can...Ch. 11 - A chemical called dioxin present in Agent Orange,...Ch. 11 - There are genetic tests for several types of...
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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.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_forwardThe 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+arrow_forward
- 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+arrow_forward. In the tryptophan operon of E. coli, what happens when tryptophan levels get too high? tryptophan is removed from its co-repressor, causing it to detach from the operator tryptophan is removed from its co-repressor, causing it to attach to the operator tryptophan is bound to its co-repressor, causing it to detach from the operator tryptophan is bound to its co-repressor, causing it to attach to the operator all of the above occur at equal rates when tryptophan levels get too higharrow_forwardYou can determine the regulation of an unknown operon based on descriptions like those in the table below. For each row, choose whether the fact would suggest positive or negative or inducible or repressible regulation and indicate your answer with an X in the column. Only one X should appear in each row. In the presence of the signal, the structural genes are expressed. In the presence of the signal, the structural genes are not expressed. In the absence of the signal, the structural genes are expressed. In the absence of the signal, the structural genes are not expressed. The binding of the regulatory protein to the operon results in structural gene expression. The binding of the regulatory protein to the operon prevents structural gene expression. A mutation in the regulatory protein results in constitutive expression of the structural genes. A mutation in the regulatory protein results in no or low expression of the structural genes. Positive? Negative? Inducible? Repressible?arrow_forward
- 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_forwardStudy the illustration of the lac operon below. Normally, the genes are switched off when lactose is not present. Lactose activates the genes, which code for enzymes that allow the cell to use lactose. Mutations can alter the functions of this operon. Predict how the following mutations would affect the function of the operon the absence and presence of lactose. Mutation of regulatory gene; repressor will not bind to lactose. Mutation of operator; repressor will not bind to operator. Mutation of regulatory gene; repressor will not bind to operator. Mutation of promoter; RNAP will not attach to promoter.arrow_forwardWhen 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_forward
- All of the following statements about the repressor of the lac operon of E. coli are true EXCEPT which one? O A. The repressor is the product of a regulatory gene i The repressor binds to the operator region of the DNA of the lac OB. operon. The repressor is a protein. OC. The repressor interacts with the operator in such a way as to OD. prevent translation of beta-galactosidase. The repressor can combine with lactose to form a OE. complex that will no longer bind to the operator region. QUESTION 32 The amino acid which is a precursor of serotonin is Histidine OA. O B. Tyrosine O C. Glutamate D. Tryptophan O E. none of the abovearrow_forwardA mutation at the operator prevents the regulator protein from binding. What 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.arrow_forwardYou 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, answer the following questions Which operons would be functional under these conditions? 2. What repressors would be made? (NOTE: name the repressors using their gene names) 3.Which repressor(s) would be made in the inactive form? 4.Which repressor(s) would be made in the active form? 5.Which repressor(s) under these conditions can bind the operator sequence? 6.Which repressor(s)under these conditions cannot bind the operator sequence?arrow_forward
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