Answer as Directed. Below is the model of a lac operon.lac Ilac Zсpromoter operatorlac Ylac ADNA+11. What are structural genes? Are the lac structural genes transcribed in the absence oflactose?2. What is the role of the promoter and operator sites in the operon?3. Is the repressor protein bound to the operator site in the absence of lactose? In itsabsence?4. Under what nutritional circumstances (high or low glucose) is CAP bound to cAMP?5. 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?6. 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 transcribedthen?7. In the presence of lactose and the absence of glucose in the bacterial growth media,what proteins are bound to the lac control region?8. Why is it adaptive for a bacterium to not express the genes that encode for that lactoseutilization proteins when lactose is not available or when glucose is present?9. Why is it adaptive for the structural genes for using lactose to be under the control of asingle promoter, i.e., synthesize a polycistronic message rather than threemonocistronic message?

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Answer as Directed. Below is the model of a lac operon. lac I lac Z с promoter operator lac Y lac A DNA +1 1. What are structural genes? Are the lac structural genes transcribed in the absence of lactose? 2. What is the role of the promoter and operator sites in the operon? 3. Is the repressor protein bound to the operator site in the absence of lactose? In its absence? 4. Under what nutritional circumstances (high or low glucose) is CAP bound to cAMP?

Answer as Directed. Below is the model of a lac operon. lac I lac Z с promoter operator lac Y lac A DNA +1 1. What are structural genes? Are the lac structural genes transcribed in the absence of lactose? 2. What is the role of the promoter and operator sites in the operon? 3. Is the repressor protein bound to the operator site in the absence of lactose? In its absence? 4. Under what nutritional circumstances (high or low glucose) is CAP bound to cAMP?

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?
Read aloud V Draw Highlight 2. You are studying the regulation of the lactose operon in Escherichia coli, by measuring expression of the lacZ gene (i.e production of beta-galactosidase). (a) You identify several loss-of-function mutations in which lacZ is never expressed, in the presence and absence of glucose and lactose. What components of the lac operon could be mutated to produce this phenotype? List all possibilities. (b) You identify another loss-of-function mutation with the following expression pattern: Media + glucose - lactose + glucose +lactose - glucose - lactose - glucose + lactose lacZ expression Low Low High High What components of the lac operon could be mutated to produce this phenotype? List all possibilities.
. 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.
Plz answer ASAP. I will thumb up You are studying the regulation of the lactose operon in Escherichia coli, by measuring expression of the lacZ gene (i.e production of beta-galactosidase).(a) You identify several loss-of-function mutations in which lacZ is never expressed, in the presence and absence of glucose and lactose. What components of the lac operon could be mutated to produce this phenotype? List all possibilities.
The molecules indicated below can be used experimentally due to their roles in relation to the expression of the lac operon. Drag the listed molecules to their corresponding bin. Reset Help ONPG IPTG X-Gal allolactose Dragable beta-galactosidase cleaves this molecule to form a visible yellow product. beta-galactosidase cleaves this molecule which then dimerizes to form a visible blue product. This molecule induces the transcription of the lac operon by inactivating the lac repressor.
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 Pregulator P operon Hexose Operon Genes regulator promoter operon promoter
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
Operons A. Draw a schematic of the lac operon when glucose is low and lactose is high in the cell’s environment. B. Draw a schematic of the trp operon when tryptophan levels in the environment are low. C. What is the lux operon and how is affected by quorum sensing?
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?
Explain why (a) inactivation of the O2 or O3 sequence of the lac operon causes only a twofold loss in repression, and (b) inactivation of both O2 and O3 reduces repression ∼70-fold.
Supply the words “off" or “on" in the blanks below: In an inducible operon, transcription is normally and must be turned In a repressible operon, transcription is normally and must be turned Briefly describe the overall function of the structural genes in the lac operon. Briefly describe the overall function of the structural genes in the trp operon. For the following descriptions of the bacterial lac operon, determine if lactose is present (P) or absent (A). The repressor is bound to the operator. The repressor is inactive. RNA polymerase transcribes the structural genes. Allolactose is bound to the repressor For the following descriptions of the bacterial trp operon, determine if tryptophan levels are high (H) or low (L). The repressor is bound to the operator. The repressor is inactive. RNA polymerase transcribes the structural genes. Tryptophan is bound to the repressor.
. Mutants were isolated in which the constitutive phenotype of a missense lacI mutation was suppressed.That is, the operon was now inducible. These suppressor mutations mapped to the operon, not to the lacIgene. What could these mutations be?