Biology: The Dynamic Science (MindTap Course List)
4th Edition
ISBN: 9781305389892
Author: Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher: Cengage Learning
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Chapter 16, Problem 2TYK
For the E. coli lac operon, when lactose is present:
a. and glucose is absent, cAMP binds and activates catabolicactivator protein (CAP).
b. and glucose is absent, the level of cAMP decreases.
c. activated CAP binds the repressor protein to remove it from the operator gene.
d. the cell prefers lactose over glucose.
e. RNA polymerase cannot bind to the promoter.
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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 protein
Explain 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.
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.
Chapter 16 Solutions
Biology: The Dynamic Science (MindTap Course List)
Ch. 16.1 - Suppose the lacl gene is mutated so that the Lac...Ch. 16.1 - Answer the equivalent question for the trp operon:...Ch. 16.2 - What is the role of histones in gene expression?...Ch. 16.2 - Prob. 2SBCh. 16.3 - Prob. 1SBCh. 16.3 - Prob. 2SBCh. 16.4 - Prob. 1SBCh. 16.4 - Prob. 2SBCh. 16.5 - Prob. 1SBCh. 16.5 - Prob. 2SB
Ch. 16.5 - Prob. 3SBCh. 16.5 - Prob. 4SBCh. 16 - Prob. 1TYKCh. 16 - For the E. coli lac operon, when lactose is...Ch. 16 - Prob. 3TYKCh. 16 - Prob. 4TYKCh. 16 - Prob. 5TYKCh. 16 - Prob. 6TYKCh. 16 - Prob. 7TYKCh. 16 - Prob. 8TYKCh. 16 - Prob. 9TYKCh. 16 - Prob. 10TYKCh. 16 - Discuss Concepts In a mutant strain of E. coli,...Ch. 16 - Prob. 12TYKCh. 16 - Prob. 13TYKCh. 16 - Prob. 14TYKCh. 16 - Design an experiment using rats as the model...Ch. 16 - Prob. 1ITDCh. 16 - Prob. 2ITDCh. 16 - Prob. 3ITDCh. 16 - Prob. 4ITD
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- 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_forwardWhich 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_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 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_forward
- IPTG (isopropylthiogalactoside) is commonly used to induce protein expression in Lac operon-regulated gene in E. Coli, because IPTG a. is a repressor to Lac operon. O b. is an enhancer binding compound. O C. O d. unwinds DNA, leading to DNA duplication and transcription. is a mimetic of allolactose, that binds to repressor, causing it release from the operator of the lac operon, leading to transcription.arrow_forwardThere 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_forwardIf 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 operatorarrow_forward
- Imagine this scenario: In E.coli the Operon X encodes for Proteins Y, X and Z. Proteins Y, X and Z are required for growth in the presence of Drug A. Outline the experiments that you would conduct to assess whether Protein B represses the transcription of Operon X in the absence of Drug A. Things to consider: 1. Transcription of Operon X 2. Mutations 3. Chromatin structurearrow_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_forwardFor the lac operon, determine whether genes will be expressed (on) or silenced (off) given the following: a. Lactose levels are high, glucose is low. b. The lac repressor can no longer bind DNA; lactose and glucose are low.arrow_forward
- 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 attenuationarrow_forwardConsider the lac operon of E. coli. Specifically, explain the following: a. Describe the overall chromosomal structure/organization of the operon, indicating the location and function of the regulatory regions and the structural genes. b. Is lac a catabolic or anabolic pathway? Explain. Is the operon inducible or repressible? Explain. c. Describe the mechanisms involved in negative control & positive controlarrow_forwardWhich of the following statements is true regarding transcriptional attenuation of the trp operon? a. The leader peptide encodes a protein that binds to the operator site b. Translation of the leader peptide stalls when tryptophan levels are high c. Stalling of the ribosome in region 1 of the leader peptide inhibits formation of the transcriptional terminator sequence d. This kind of mechanism can only occur in prokaryotes e. Both c. and d. are truearrow_forward
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