Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Chapter 14, Problem 8CONQ
Summary Introduction
To review:
The expression of the gene, if the following segments were missing:
A. lac operon promoter
B. operator site.
C. lac A gene.
Introduction:
The lac operon in E.coli (Escherichia coli) has set of four genes, which work together to allow the bacterium to use lactose for energy. The lac operon of E.coli contains genes involved in lactose
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Check out a sample textbook solutionStudents have asked these similar questions
In the lac operon, how would gene expression be affected if each one of the following segments was missing?
A. lac operon promoter
B. Operator site
C. lacA gene
If lactose isn't present in the environment of an E. coli, what is the state of the lac operon?
O a. It is "on" (high transcription) because will glucose will still be present, so the operon's products will be needed.
O b. It is "on" (high transcription) because CAP will be bound to the promoter
O c. It is "off" (no transcription) because RNA polymerase will be inactivated
d. It is "off" (no transcription) and the repressor will be bound to the operator
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 14 Solutions
Genetics: Analysis and Principles
Ch. 14.1 - 1. A repressor is a __________ that _________...Ch. 14.1 - 2. Which of the following combinations will cause...Ch. 14.2 - 1. What is an operon?
a. A site in the DNA where...Ch. 14.2 - The binding of _______ to lac repressor causes lac...Ch. 14.2 - Prob. 3COMQCh. 14.2 - How does exposing an E. coli cell to glucose...Ch. 14.3 - When tryptophan binds to trp repressor, this...Ch. 14.3 - During attenuation, when tryptophan levels are...Ch. 14.3 - Operons involved with the biosynthesis of...Ch. 14.4 - 1. Translation can be regulated by
a....
Ch. 14.4 - Prob. 2COMQCh. 14.5 - 1. For a riboswitch that controls transcription,...Ch. 14 - 1. What is the difference between a constitutive...Ch. 14 - In general, why is it important to regulate genes?...Ch. 14 - Prob. 3CONQCh. 14 - Transcriptional regulation often involves a...Ch. 14 - An operon is repressible-a small effector molecule...Ch. 14 - Prob. 6CONQCh. 14 - 7. What is enzyme adaptation? From a genetic point...Ch. 14 - Prob. 8CONQCh. 14 - Prob. 9CONQCh. 14 - Prob. 10CONQCh. 14 - Mutations may have an effect on the expression of...Ch. 14 - 12. Would a mutation that inactivated lac...Ch. 14 - Prob. 13CONQCh. 14 - 14. As shown in Figure 14.12, four regions within...Ch. 14 - 15. As described in Chapter 13, enzymes known as...Ch. 14 - 16. The combination of a 3–4 stem-loop and a...Ch. 14 - 17. Mutations in tRNA genes can create tRNAs that...Ch. 14 - Prob. 18CONQCh. 14 - Prob. 19CONQCh. 14 - A species of bacteria can synthesize the amino...Ch. 14 - 21. Using three examples, describe how allosteric...Ch. 14 - How are the actions of lac repressor and trp...Ch. 14 - 23. Transcriptional repressor proteins (e.g., lac...Ch. 14 - Answer the following questions that pertain to the...Ch. 14 - Chapter 21 describes a blotting method known as...Ch. 14 - As described in experimental question E2 and also...Ch. 14 - Prob. 4EQCh. 14 - Explain how the data shown in Figure 14.9 indicate...Ch. 14 - Prob. 6EQCh. 14 - Lets suppose you have isolated a mutant strain of...Ch. 14 - Prob. 1QSDCCh. 14 - Prob. 2QSDC
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- A 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_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_forwardMutations 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 attenuationarrow_forward
- A 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 trp operon in E. coli is a negative repressible operon. This implies that... a. The trp operon makes use of an activator and can be turned "on" (i.e., is normally "off") b. The trp operon makes use of an activator and can be turned "off" (i.e., is normally "on) c. The trp operon makes use of a repressor and can be turned "on" (i.e., is normally "off") d. The trp operon makes use of a repressor and can be turned "off" (i.e., is normally "on") e. None of the abovearrow_forwardIn the trp operon, tryptophan is best characterized as being a: A. repressor B. inducer C. corepressor D. DNA-binding domainarrow_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_forwardControl of the trp operon relies on which of the following: a. High levels of tryptophan causing a pause (but not termination) in transcription b. Low levels of tryptophan causing a pause (but not termination) in transcription c. Allolactose binding to the inhibitor to prevent it from binding to the promoter d. Tryptophan binding to the inhibitor to prevent it from binding to the promoterarrow_forwardExplain how the lac operon is regulated under the following conditions. Include the following terms in your answers: Repressor, Operator, RNA polymerase, CAP site, CAP protein, Promoter A. Lactose and glucose are both present. B. Lactose and glucose are both absent. C. Lactose is present and glucose is absent.arrow_forward
- Which of the following describes the lac operon in E. coli when lactose and glucose is present in the culture medium? Select one: a. CAP inactive and RNA polymerase does not completely bind to the promoter of the lac operon and transcription of lactose-metabolizing enzymes decreases. b. CAP is active and RNA polymerase binds completely to the promoter of the lac operon and transcription of lactose-metabolizing enzymes decreases. c. Catabolite activator protein (CAP) inactive and RNA polymerase does not completely bind to the promoter of the lac operon and transcription of lactose-metabolizing enzymes increases. d. CAP is active and RNA polymerase binds completely to the promoter of the lac operon and transcription of lactose-metabolizing enzymes increases.arrow_forwardWhat would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator? (Explain what would happen both in the presence and absence of lactose)arrow_forwardDecide which operon each of the following characteristics applies to. Note: a description may apply to both. a. lac operon b. trp operon 68. repressible 69. Turned off when end product is present (feedback inhibition) 70. Promoter, activator region, and 3 genes 71. Repressible 72. contain operator and promoter regions as well as transcript units of at least two or more coding genes 73. Codes for catabolic enzymes that break down lactose 74. Inducible 75. Promoter, activator region, and 5 genes 76. Codes for anabolic enzymes that help manufacture tryptophan 77. Lactose is the co-inducer 78. Turned on when substrate is present 79. Tryptophan is the co-repressor 80. Regulatory gene segmentsarrow_forward
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