fluctuating Proteolytic cleavage is used to inactivate repressors in an essentially process, such as involves in activation of a viral reproduction program. Repressor inactivation by binding a small molecule allows for changes in gene expression under conditions where concentrations of metabolites does not involve in the medium might be and it the wasteful degradation and reversible resynthesis of regulatory proteins. constant irreversible

fluctuating Proteolytic cleavage is used to inactivate repressors in an essentially process, such as involves in activation of a viral reproduction program. Repressor inactivation by binding a small molecule allows for changes in gene expression under conditions where concentrations of metabolites does not involve in the medium might be and it the wasteful degradation and reversible resynthesis of regulatory proteins. constant irreversible

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Description: Question Attached: about lac operon fluctuatingProteolytic cleavage is used to inactivate repressors in an essentiallyprocess, such asinvolvesin activation of a viral reproduction program. Repressor inactivation by binding a small molecule allowsforc

Biology Today and Tomorrow without Physiology (MindTap Course List)

5th Edition

ISBN:9781305117396

Author:Cecie Starr, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Christine Evers, Lisa Starr

Chapter7: Gene Expression And Control

Section: Chapter Questions

Problem 15SQ

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Scientists have exploited the siRNA pathway toperform a technique called RNA interference—ameans to knock down the expression of a specificgene without having to make mutations in it. Theidea is to introduce dsRNA corresponding to thetarget gene into an organism; the dsRNA is thenprocessed into an siRNA that leads to the degradation of the target gene’s mRNA. One clever methodfor delivery of the dsRNA to some organisms (thenematode C. elegans, for example) is to feed thembacteria transformed with a recombinant plasmidthat expresses dsRNA.a. Draw a gene construct that, when expressed from aplasmid in bacteria, could be used to knock downby RNA interference the expression of gene X ofC. elegans.b. How can you test if gene X expression is obliterated in worms that have eaten the bacteria transformed with a plasmid containing your construct?c. Do you think that only gene X expression will beaffected in these worms? Explain.
Certain environmental conditions such as exposure to UV light areknown to activate lysogenic λ prophages and cause them to progressinto the lytic cycle. UV light initially causes the repressor protein to be proteolytically degraded. Make a flow diagram showing the subsequent events that lead to the lytic cycle. (Note: The xis gene codes for an enzyme that is necessary to excise the λ prophage from the E. coli chromosome. The enzyme integrase is also necessary for this excision.)
Cells go to great length to correctmistakes in the processes of DNAreplication, transcription, splicing,and translation. Are there analogousstrategies to correct mistakes in theselection of which genes are to beexpressed in a given cell type? Couldthe great complexity of transcriptioninitiation in animals and plants reflectsuch a strategy?
Linezolid is a new type of antibiotic that inhibits protein synthesis in several bacterial species by bindingto the 50S subunit of the ribosome and inhibiting its ability to participate in the formation of translationalinitiation complexes. Physicians are particularlyinterested in this antibiotic for treating pneumoniacaused by penicillin-resistant Streptococcus pneumoniae (also called pneumococci). To explore themechanisms by which pneumococci can developresistance to linezolid, you first want to identifylinezolid-resistant strains. Next, using one of thesestrains as starting material, you want to identifyderivatives of these mutants that are no longertolerant of linezolid.a. Outline the techniques you would use to identifylinezolid-resistant mutant pneumococci andlinezolid-sensitive derivatives of these mutants.In each case, would your techniques involve directselection, screening, replica plating, treating withmutagens, or testing for a visible phenotype?b. Suggest possible…
The intermediates A, B, C, D, E, and F all occur inthe same biochemical pathway. G is the product of thepathway, and mutants 1 through 7 are all G−, meaningthat they cannot produce substance G. The followingtable shows which intermediates will promote growthin each of the mutants. Arrange the intermediates inorder of their occurrence in the pathway, and indicatethe step in the pathway at which each mutant strain isblocked. A + in the table indicates that the strain willgrow if given that substance, an O means lack of growth.SupplementsMutant A B C D E F G1 + + + + + O +2 O O O O O O +3 O + + O + O +4 O + O O + O +5 + + + O + O +6 + + + + + + +7 O O O O + O +
Certain hormones, such as epinephrine, can increase the levels ofcAMP within cells. Let’s suppose you pretreat cells with or withoutepinephrine and then prepare a cell extract that contains theCREB protein.You then use an electrophoretic mobility shift assay to analyzethe ability of the CREB protein to bind to a DNA fragmentcontaining a cAMP response element (CRE). Describe what theexpected results would be.
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
Suppose that you have isolated a mutant strain of E. coli inwhich the lac operon is constitutively expressed. To understandthe nature of this defect, you create a merozygote in which themutant strain contains an F′ factor with a normal lac operonand a normal lacI gene. You then compare the mutant strain andthe merozygote with regard to their β-galactosidase activities inthe presence and absence of lactose. You obtain the followingresults:
One of the main lessons of this chapter is that severalbacterial genes are often transcribed from a singlepromoter into a large multigene (polycistronic) transcript. The region of DNA containing the set of genesthat are cotranscribed, along with all of the regulatoryelements that control the expression of these genes, iscalled an operon.a. Which of the mechanisms in the following listcould explain differences in the levels of themRNAs for different operons?b. Which of the mechanisms in the following listcould explain differences in the levels of theprotein products of different genes in the sameoperon?i. Different promoters might have different DNAsequences.ii. Different promoters might be recognized bydifferent types of RNA polymerase.iii. The secondary structures of mRNAs might differ so as to influence the rate at which they aredegraded by ribonucleases.PROBLEMSProblems 575a. Why did the mating with a nonlysogenic recipientresult in phage growth and release, but the infectionof a…
Many viruses that infect eukaryotic cells express genes that alterthe regulation of host gene expression to promote viral replication.For example, herpes simplex virus-1 (HSV-1) expresses aprotein called ICP0, which is necessary for successful viral infectionand replication within the host. Lutz et al. (2017. Viruses9: 210) showed that ICP0 can act as a ubiquitin ligase and targetthe redundant transcriptional repressors ZEB1 and ZEB2,which leads to upregulation of the miR-183 cluster (a set of threemiRNAs transcribed from the same locus). Speculate on how miR-183 cluster upregulation may benefitthe virus.
Many viruses that infect eukaryotic cells express genes that alterthe regulation of host gene expression to promote viral replication.For example, herpes simplex virus-1 (HSV-1) expresses aprotein called ICP0, which is necessary for successful viral infectionand replication within the host. Lutz et al. (2017. Viruses9: 210) showed that ICP0 can act as a ubiquitin ligase and targetthe redundant transcriptional repressors ZEB1 and ZEB2,which leads to upregulation of the miR-183 cluster (a set of threemiRNAs transcribed from the same locus). How may ICP0 expression in a host cell lead to upregulationof the miR-183 cluster?
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?