ferR 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 transcription of the ferP-ferZ genes in high iron? Genotype in genome low iron? Wild-type Nonfunctional ferR mutant fer operator

ferR 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 transcription of the ferP-ferZ genes in high iron? Genotype in genome low iron? Wild-type Nonfunctional ferR mutant fer operator

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter14: Gene Regulation

Section: Chapter Questions

Problem 13TYU: INTERPRET DATA Develop a simple hypothesis that would explain the behavior of each of the following...

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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?
Like the lac operon, the hexose operon is controlled by a separate regulatory protein under the control of its own promoter (see the schematic of the operon below). The hexose regulatory protein is sensitive to fatty acyl CoA levels. When all hexose fuel sources are depleted, the bacteria switch to lipid metabolism and fatty acyl CoA levels increase. This turns expression of the hexose operon off. +1 +1 Regulatory Gene P regulator Hexose Operon Genes operon regulator promoter operon promoter e. The regulatory protein that controls expression of the hexose operons is a transcriptional ACTIVTOR or REPRESSOR (circle one).
For each of the ff. scenario, state whether the gene is up- or down-regulated and briefly explain the reason behind. 5’-------enhancer------insulator-----gene of interest----3’
m.. In the figure below, the bacterial activator protein CAP and the Lac repressor have been placed in the four possible combinations on their binding sites in the promoter for the Lac operon. Each combination of gene regulatory proteins corresponds to a particular mixture of glucose and lactose. For each of the four combinations, indicate on the left-hand side of the figure which sugars must be present and, on the right-hand side, whether the operon is expected to be turned on or off. RNA- polymerase- start site for RNA synthesis CAP- binding binding site site (promoter) operator Lacz gene GLUCOSE LACTOSE OPERON ACTIVITY Lac repressor CAP Lac repressor CAP 60 40 40 80 nucieatide pairs
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?
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 RNA polmer 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 |
. Recall that the trp operon has a special leader sequence (trpL) between the operator and the structural genes that offers attenuation as a mechanism for regulation of gene expression. (A) Draw a diagram of a trpL region of the operon when tryptophan is abundant in the cell.Label the following features: the DNA, 5’ and 3’ polarity of the RNA, the regions 1, 2, 3,and 4 and poly-U of the RNA, the pair of Trp codons (UGG), the ribosome, and RNA-Pol,along with any stem-loop structure that would form under these conditions (B) In the above example, will the rest of the trp operon genes be expressed? Briefly describe your reasoning why or why not (C) The trp codons in region 1 of the trpL gene have mutated to cysteines (UGG to UGC). What will be the effect on attenuation gene regulation of the trp operon? Brieflyexplain your reasoning.
E27. A cloned gene fragment contains a regulatory element that is recog- nized by a regulatory transcription factor. Previous experiments have shown that the presence of a hormone results in transcriptional acti- vation by this transcription factor. To study this effect, you conduct a electrophoretic mobility shift assay and obtain the following results: Tube: 1 2 3 Transcription factor: Hormone: Explain the action of the hormone.
Identify the labeled factors in the figure below (A and B) and indicate the direction of transcription. ts A O A= Mediator, B= TFIID; direction is into the screen O A= TEIIE, B= TFIIH; direction is into the screen rences A= TBP, B= TEIIB; direction is out of the screen O A= TFIIF, B= TFIIE; direction is out of the screen
TAN TTGC IGGAG Nanog regulatory sequence Given this interaction map which DNA sequence would the transcription factor most likely bind to? CAAGGAG ATTAACG TAATTGG TAATTGC
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
a. What is the function of operons in bacterial gene regulation? b. Describe how a bacterial operon can be regulated by repressible proteins (such as the tryptophan operon). Include in your description both the “on” and “off” states of the operon. Key elements of your diagram should include: Co-repressor, Genes, mRNA, Operator, Operon, Promoter, Repressor, RNA polymerase.