BIOLOGY 2E
2nd Edition
ISBN: 9781506699851
Author: OpenStax
Publisher: XANEDU PUBLISHING
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Textbook Question
Chapter 16, Problem 9RQ
The a/a operon is an inducible operon that controls the production of the sugar arabinose. When arabinose is present in a bacterium it binds to the protein AraC, and the complex binds to the initiator
site to promote transcription. In this scenario, AraC is a(n).
- activator
- inducer
- repressor
- operator
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Students have asked these similar questions
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 above
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)
I+ OC Z+
I+ O+ Z+
(Lactose
present)
I- O+ Z+
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+
Chapter 16 Solutions
BIOLOGY 2E
Ch. 16 - Figure 16.5 In E. coli, the tip operon is on by...Ch. 16 - Figure 16.7 In females, one of the two X...Ch. 16 - Figure 16.13 An increase in phosphorylation levels...Ch. 16 - Control of gene expression in eukaryotic cells...Ch. 16 - Post-translational control refers to: regulation...Ch. 16 - How does the regulation of gene expression support...Ch. 16 - If glucose is absent, but so is lactose, the lac...Ch. 16 - Prokaryotic cells lack a nucleus. Therefore, the...Ch. 16 - The a/a operon is an inducible operon that...Ch. 16 - What are epigenetic modifications? the addition of...
Ch. 16 - Which of the following are true of epigenetic...Ch. 16 - The binding of _____ is required for transcription...Ch. 16 - What will result from the binding of a...Ch. 16 - A scientist compares the promoter regions of two...Ch. 16 - Which of the following are involved in post...Ch. 16 - Binding of an RNA binding protein will the...Ch. 16 - An unprocessed pre-mRNA has the following...Ch. 16 - IS. Alternative splicing has been estimated to...Ch. 16 - Post-translational modifications of proteins can...Ch. 16 - A scientist mutates elF-2 to eliminate its GTP...Ch. 16 - Cancer causing genes are called transformation...Ch. 16 - Targeted therapies are used in patients with a set...Ch. 16 - Name two differences between prokaryotic and...Ch. 16 - Describe how controlling gene expression will...Ch. 16 - Describe how transcription in prokaryotic cells...Ch. 16 - What is the difference between a repressible and...Ch. 16 - In cancer cells, alteration to epigenetic...Ch. 16 - A scientific study demonstrated that rat mothering...Ch. 16 - Some autoimmune diseases show a positive...Ch. 16 - A mutation within the promoter region can alter...Ch. 16 - What could happen if a cell had too much of an...Ch. 16 - A scientist identifies a potential transcription...Ch. 16 - Describe how RBPs can prevent miRNAs from...Ch. 16 - How can external stimuli alter...Ch. 16 - Protein modification can alter gene expression in...Ch. 16 - Alternative forms of a protein can be beneficial...Ch. 16 - Changes in epigenetic modifications alter the...Ch. 16 - A scientist discovers a virus encoding a Protein X...Ch. 16 - New drugs are being developed that decrease DNA...Ch. 16 - How can understanding the gene expression pattern...
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- A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcriptionarrow_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_forwardThe trp operon in E. coli encodes enzymes essential for the biosynthesis of tryptophan. In the operon, trpR gene encodes the repressor. A trpR repressor cannot bind tryptophan. The trpO is the operator. trpA encodes the enzyme tryptophan synthetase. For the enzyme (A), indicate with a + or-whether or not it is made when there is tryptophan and when there is no tryptophan. Without Tryptophan With Tryptophan R'O A /R* O' A R'O' A/R* Oʻ A R*OA/R' O Aarrow_forward
- Tryptophan (Trp) attenuation is an extra mechanism of regulation of trp operon when trp level is too high. Attenuation causes premature transcription termination. b) Predict what will happen if trp repressor lose its allosteric effect.arrow_forwardWhat would happen if the operator sequence of the trp operon contained a mutation that prevented the repressor protein from binding to the operator? (Explain what would happen in both the presence and absence of tryptophan)arrow_forwardGiven the Table below concerning the lac operon, match the letter with what would be occurring for each scenario. Repressor is bound to the operator, cAMP complex is bound and transcription is prevented. Allolactose is bound to the repressor, cAMP complex is bound, and transcription is prevalent. Allolactose is bound to the repressor, cAMP complex is not assembled, and transcription is slow Repressor is bound to the operator, cAMP complex is not assembled, and transcription is prevented.arrow_forward
- A theoretical operon (theo) in E. coli contains several structural genes encoding enzymes that are involved sequentially in the biosynthesis of an amino acid. Unlike the lac operon, in which the repressor gene is separate from the operon, the gene encoding the regulator molecule is contained within the theo operon. When the end product (the amino acid) is present, it combines with the regulator molecule, and this complex binds to the operator, repressing the operon. In the absence of the amino acid, the regulatory molecule fails to bind to the operator, and transcription proceeds. Characterize this operon, then consider the following mutations, as well as the situation in which the wild-type gene is present along with the mutantgene in partially diploid cells (F¿):(a) Mutation in the operator region.(b) Mutation in the promoter region.(c) Mutation in the regulator gene.In each case, will the operon be active or inactive in transcription, assuming that the mutation affects the…arrow_forwardThe map of the lac operon is: POZY The promoter (P) region is the start site of transcription through the binding of the RNA polymerase molecule before actual MRNA production. Mutationally altered promoters (P') cannot bìnd the RNA polymerase molecule. Certain predictions can be made about the effect of P mutations. Use your knowledge of the lactose system to complete the table below. Insert a "+" where enzyme is produced and a "-" where enzyme is not produced. Indicate whether the partial diploid strain is lac* (able to grow on lactose-only medium) or lac( cannot grow in lactose medium). B-Galactosidase Permease Phenotype (Lac or Number Genotype No Lactose Lactose No Lactose Lactose Lac) P*O*Z*Y# Example lac+ I*p*O*z*Y* a Ip*o+z*Y* I*p*oCz*Y C I*p*o+z*Yarrow_forwardWhich of the following statements about the trp operon is false? If a mutation in region 2 prevents the formation of the 2 + 3 loop in the 5’UTR transcription levels will increase. The trp operon is an example of negative repressible operon. Formation of the anti-terminator in the 5’UTR of the trp operon occurs when trp levels are low. In the presence of high trp-tRNA, the genes of the trp operon are not expressed. The role of trp is to bind to the repressor protein and activate it.arrow_forward
- Which of the following conditions is most likely to result in an increase rate of transcription of the lac operon? when lactose is present AND the repressor is permanently attached to the operator when lactose is present and there is high levels of glucose when lactose is absent and there are low levels of glucose when lactose is present and there are low levels of glucosearrow_forwardTryptophan (Trp) attenuation is an extra mechanism of regulation of trp operon when trp level is too high. Attenuation causes premature transcription termination. c) Review the region that is responsible for trp attenuation during low trp level.arrow_forwardA bacterial operon is responsible for the production of the biosyntheticenzymes needed to make the hypothetical amino acidtisophane (tis). The operon is regulated by a separate gene, R.The deletion of R causes the loss of enzyme synthesis. In the wildtypecondition, when tis is present, no enzymes are made; in theabsence of tis, the enzymes are made. Mutations in the operatorgene (O-) result in repression regardless of the presence of tis. Isthe operon under positive or negative control? Propose a modelfor (a) repression of the genes in the presence of tis in wild-typecells and (b) the mutations.arrow_forward
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