Operator | Choose Choose) A set of genes transcribed together under the regulatory control of a singe promoter A regulatory protein that binds to an region of non-coding DNAgene that suppresses transcriptionby blocking RApolmer A segment of DNA where the repressor binds to, therety preventing the transcription of certain genes An operon that isalways "off" - turned on by environmental cues an operon that isalways "on"-turned off by environmental cues TChoose] Operon Repressor Repressible Operon [ Choose] nducible operon [Choose

Operator | Choose Choose) A set of genes transcribed together under the regulatory control of a singe promoter A regulatory protein that binds to an region of non-coding DNAgene that suppresses transcriptionby blocking RApolmer A segment of DNA where the repressor binds to, therety preventing the transcription of certain genes An operon that isalways "off" - turned on by environmental cues an operon that isalways "on"-turned off by environmental cues TChoose] Operon Repressor Repressible Operon [ Choose] nducible operon [Choose

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter16: Gene Expression

Section: Chapter Questions

Problem 9RQ: The a/a operon is an inducible operon that controls the production of the sugar arabinose. When...

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P. fgrR OP ferP ferS ferI ferZ KEY: O = operator P= promoter Boxes = structural genes Arrows = transcription start sites A hypothetical operon is shown above. At high iron levels, ferR binds a molecule of iron and the complex then binds the fer operator and prohibits transcription. When iron levels are low, the molecule of iron bound to ferR is used, which causes a conformational change so that ferR is released from the operator. a. Trypotphan is the effector molecule in the trp operon. What would be the equivalent molecule in this operon? b. Under what environmental condition will ferR be bound to the operator: high iron or low iron? c. Complete the table as to the expected transcription of different genotypes in high and low iron concentrations. yes = transcription, no = no transcription Genotype in genome transcription of the ferP-ferZ genes in high iron? low iron? Wild-type Nonfunctional ferR mutant fer operator
P₁0 ORF1 t₁ ORF2 ORF3 t₂ The diagram above illustrates an operon that is regulated by the RepR protein. O A small molecule, X, is needed to enable RepR to bind to the operator (O). When X is absent, which of the following statements is most accurate? O RNA polymerase binding to the P₁ promoter is unblocked Equal amounts of ORF1, ORF2, and ORF3 are made Expression of ORF2 and ORF3 is prevented by the terminator t₁ O Expression of ORF1, ORF2, and ORF3 is de- repressed
You have created a deletion of the ribosome binding site for the leader sequence of the trp operon. If grown in low tryptophan conditions, what would be the effect of this mutation on transcription of trpe (the first ORF after the leader region in the trp operon) relative to a wild-type strain grown under similar conditions? O Increased transcription O No effect on transcription Decreased transcription
Resection of a bacterial chromosome in which genes for the enzymes of of a particular metabolic pathway are clusteredtogether in a functional complex under coordinate control is called operon activator promotor repressor operator
amount of protein / amount of mRNA 12 mm / ↑ A B time (minutes) 20 Bacteria were grown in culture. At various time points, substances were added or removed from the culture medium. To assay the effects of the substances on operon gene expression, samples of bacteria were collected at one-minute intervals and levels of specific proteins and mRNAs were determined. If the operon under investigation is a repressible operon, which arrow indicates the addition of a molecule that binds the repressor protein?
Please match the gene element with the the correct definition. control elements 5' UTR 3' UTR Promoter coding region +1 site [Choose ] stretch of DNA that contains the sequence that will encode the protein the active form of RNA polymerase region of DNA upstream of transcription start site that is recognized by RNA polymerase region of mRNA on the 5' end that goes untranslated RNA polymerase and the sigma factor regions of DNA that increase or decrease transcription rate the first nucleotide to be transcribed region of mRNA on the 3' end that goes untranslated a transcription initiation factor that helps RNA polymerase recognize the promoter the inactive form of RNA polymerase [Choose ] [Choose ]
iestiðn Pre-initiation complex (PIC) is formed right before the initiation of genes, which of the following steps seemes to NOT help for the PIC formation? O TBP protein to recognize TATA box at promoter region O TFIIA to recognize the TAFS in TFIID O Enhancers to attract coactivators and activators O Silencers to attract repressor and corepressors
Answer as Directed. Below is the model of a lac operon. lac I lac Z с promoter operator +1 lac Y lac A DNA 1. In the absence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac control region? Is the operon being transcribed then? 2. In the presence of lactose and the presence of glucose in the bacterial growth media, what proteins are bound to the lac regulatory region? Is the operon being transcribed then? 3. In the presence of lactose and the absence of glucose in the bacterial growth media, what proteins are bound to the lac control region? 4. Why is it adaptive for a bacterium to not express the genes that encode for that lactose utilization proteins when lactose is not available or when glucose is present? 5. Why is it adaptive for the structural genes for using lactose to be under the control of a single promoter, i.e., synthesize a polycistronic message rather than three monocistronic message?
Tonly in cell biology the Lac operon in bacteria encodes proteins required to import and digest the disaccharide lactose in the absence of glucose. Lac operon is highly expressed only when two conditions are met: glucose must be absent and lactose must be present. Bacteria solves this issue by employing both an activator and a repressor for the same operon. But how? A Bacteria can turn on Lac operon even if the repressor is bound to the operator region. B When the two conditions are met repressor will not be present, activator will be active. Thus the operon will be ON. C Operon is always on when the repressor is not bound. D Operon will be off when the activator is bound and repressor is not. E Activators itself inhibit repressors from binding to operators.
The promoter of an operon is the site to which RNApolymerase binds to begin transcription. Certain basechanges in the promoter result in a mutant site towhich RNA polymerase cannot bind. Would you expect mutations in the promoter that prevent binding ofRNA polymerase to act in trans on another copy ofthe operon on a plasmid in the cell, or only in cis onthe copy immediately adjacent to the mutated site?
The transcription of a gene called YFG (your favoritegene) is activated when three transcription factors (TFA,TFB, TFC) interact to recruit the co-activator CRX. TFA,TFB, TFC, and CRX and their respective binding sitesconstitute an enhanceosome located 10 kb from the transcription start site. Draw a diagram showing how youthink the enhanceosome functions to recruit RNA polymerase to the promoter of YFG.
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.