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Name: Cell and Molecular Biology Subject:1. Explain how the actions of the l
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Description: Cell and Molecular Biology Subject:1. Explain how the actions of the lac operon are different from the trp operon. 2. Why is it important for a multicellular organism to be able to turn on only some of its genes in any particular tissue or cell type?

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Biology

. Explain how the actions of the lac operon are different from the trp operon.

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter16: Regulation Of Gene Expression

Section: Chapter Questions

Problem 11TYK: Discuss Concepts In a mutant strain of E. coli, the CAP protein is unable to combine with its target...

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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.
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?
. 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.
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? 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 transcribed then? 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…
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.
Discuss Concepts In a mutant strain of E. coli, the CAP protein is unable to combine with its target region of the lac operon. How would you expect the mutation to affect transcription when cells of this strain are subjected to the following conditions? Lactose and glucose are both available. Lactose is available but glucose is not. Both lactose and glucose are unavailable.
1. Please tell me: What's a mutation in moleculer terms? 2. When a mutation deletes a base in genomic DNA, how does it affect the expression product production and reading frame? 3. How does induction control enzyme synthesis using lactose operon?
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
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
I. Answer the following: 1. What are the main elements of the lac operon and their functions? 2. Distinguish among inducible, repressible, and constitutive gene operons.
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).
Choose correct option and do explain plz. 1. The protein complex that helps RNA polymerase to cross nucleosomes during extension is:a. SWI-SNFb. poly A polymerasac. TFIISd. FACT 2. The polydenylation is carried out by:a. primaseb. polymers poly ac. a reverse transcriptased. adenylyltransferase 3. The lactose operon produces a polycistronic mRNA that includes four genes: Lacl, LacZ, LacY and LacA. True or false?