For some time it was not clear whether lac repressor inhibits lac operon transcription by inhibiting the binding of RNA polymerase to its pro- moter or by allowing transcription initiation but blocking elongation past the site of bound repressor. How might you distinguish between these possibilities?
Q: In the lac operon system, do the inducers act at the transcription or translation level? Explain why…
A: The lactose operon (lac operon) consists of a regulatory gene (i-gene) and three structural genes -…
Q: How does catabolite repression work on gal operon?How could you decide if one particular operon is…
A: catabolite repression : Catabolite repression is a regulatory system by which any microorganism…
Q: Attardi et al. (1963) found that lactose operon mRNA synthesis in coli increased with the addition…
A: Both structural and regulatory genes are found in genomic DNA, and both encode products that act as…
Q: Under what conditions is lac repressor bound to the lac operon?
A: Lactose operon (Lac operon) was discovered in Escherichia coli. This is studied to understand the…
Q: Mutations in bacterial promoters may increase or decrease the rate of gene transcription. Promoter…
A: Introduction Promoter are the consensus sequences found either upstream or partially downstream of…
Q: Describe the structure of the Lac operon. How is it turned on? How is it turned off?
A: The gene products of the lac operon are very important for lactose metabolism. This is crucial for…
Q: Which of the following conditions is most likely to result in an increase rate of transcription of…
A: Lactose in bacteria is called beta-galactoside which is used as energy and as a carbon source.…
Q: How does the binding of the trp corepressor and the lac inducer to their respective repressor…
A: "Since you have asked multiple questions, we will solve the first question for you. If you want any…
Q: Compare and contrast the functional mechanism of the Inducible - Lac operon with the Repressible -…
A: Gene expression is a process in which the genetic instructions of genes are utilized to manage…
Q: The arabinose operon How does the araC protein regulate of the arabinose operon. How does its…
A: How arac protein regulate arabinose operon and how binding differ If arabinose is absent, the dimer…
Q: When cAMP binds to the Catabolite Activator Protein (CAP), it causes a conformational change on the…
A: The lac operon will be expressed at high levels if the following two criteria are met: Glucose must…
Q: Consider a mutant of E. coli that has an inactivating mutation in the gene for adenylate cyclase…
A: Introduction :- Inactivating mutations, also known as loss-of-function mutations, cause the gene…
Q: m. In the figure below, the bacterial activator protein CAP and the Lac repressor have been placed…
A: Introduction :- The lac operon is a group of genes with a single promoter that encode genes for…
Q: Which of the following mutations would result in the highest level of lac operon transcription in…
A:
Q: Which enzyme will be produced in a cell where a nonsense mutation is present in the lac operon?
A: In genetics, the mutation in which a sense codon that corresponds to one of the twenty amino acids…
Q: What led researchers to conclude that a repressor moleculeregulates the lac operon?
A: Lac operon is regulated by the lac repressor molecule.
Q: Mutation in the regulatory gene in the lac operon results in the formation of an inactive repressor.…
A: The lac operon is an operon, or group of genes with a single promoter.The genes in the operon encode…
Q: Provide the SIGNIFICANT differences between the following
A: The process by which a cell regulates the conversion of DNA to RNA (transcription) and hence…
Q: As diagrammed below, some amino acid biosynthetic operons have stem loop structures in the mRNA.…
A: Option A is incorrect as without the formation of heparin the process of translation can not be…
Q: Mutations may have an effect on the expression of the lac operon and the trp operon. Would the…
A: Mutations are defined as the change in the sequence of DNA of an organism due to any environmental…
Q: Bacteria with a lac phenotype are unable to use lactose because of some defect in expressing the…
A: Answers - 1) False 2) True 3) True There are 3 structural genes in lac operon - lac Z, lac Y and…
Q: Under the following conditions, what will be occurring with the lac operon? Glucose: Present…
A: lac operon is present in E.coli and contain genes that control lactose metabolism and only active…
Q: Bacterial DNA containing an operon encoding three enzymes is introduced into chromosomal DNA in…
A: Prokaryotes are the organisms that lack the cell nucleus and membrane-bound organelles. They have…
Q: (MC) What is the function of lactose in regulation of the lac operon? 1. activates a repressor…
A: Operons are a group of enzymes and regulatory sequences.
Q: A researcher was trying to determine whether two molecules (A and B) were corepressors or inducers…
A: Gene expression is predominantly regulated at the transcriptional level, owing to protein binding to…
Q: Suppose that an operon that exhibited positive control was inducible. Would the regulator gene in…
A: An operon is defined as a group of genes that have a common promoter and regulator and also…
Q: The lac genotypes are as shown below: P+OcZ-Y+A+// P¬O+Z+Y+A+ (i) The lac operon consists of three…
A: Lac operon refers to the set of genes responsible for uptake and metabolism of lactose. Three…
Q: What conservation laws (P- or S- invariants) can be found in the lac operon regulatory Petri net?
A: The lactose operon or lac operon is an operon that is required for the transport and metabolism of…
Q: Consider the following scenario: A bacteria cell is surrounded by lactose, but there is no glucose…
A: Lac operon is an operon model takes place in E coli bacteria . It consists of :- A)Promoter B )…
Q: in the lac operon, both the operator (o1) and the binding site for CRP–cAMP show rotational…
A: Lactose operon is also called as lac operon. The operon required for the transport and metabolism of…
Q: Provide the SIGNIFICANT differences between the following: 1. Operon Systems Inducer/Lac…
A: An operon is a cluster of functional genes which are regulated by the common operator. Operons…
Q: Regarding the trp operon: when levels of tryptophan are low, the ___ hairpin forms, resulting in…
A: Trp operon is negatively regulated by tryptophan which means in low concentration of tryptophan the…
Q: Assume you have identified a new operon in bacteria (which you call the suc operon) tha encodes…
A: Any bacterial gene can be classified as an operon.An operon is a collection of bacterial genes with…
Q: You have E. coli growing in HIGH lactose and HIGH glucose. You measure the amounts of protein and…
A: The E.coli is growing in a medium rich in lactose and Glucose both. There are two regulatory…
Q: Attardi et. al (1963) found that lactose operon synthesis in E.coli increased with the addition of…
A: operon, a genetic regulatory system found in bacteria and their viruses that clusters genes coding…
Q: For some time, it was not clear whether lac repressor inhibits lac operon transcription by…
A: The binding of the lac repressor to the RNA(ribonucleic acid) polymerase of the lac transcription…
Q: Select all of the cis-acting regulatory elements of the lac operon. Operator CAP+cAMP CAP+cAMP…
A: lac operon: - Inducible system - Both positive and negative regulation - Involved in lactose…
Q: With respect to the lac operon, what is allolactose?
A: It is an operon required for the transport and metabolism of lactose in E.coli and many enteric…
Q: In regulations demonstrated by initiation of transcription, if lactose is abundant, lactose in this…
A: The promoter is a region on the lac operon which is bounded by RNA polymerase to initiates the…
Q: To characterize the promoter of the gadA operon you made a series of deletion mutants removing…
A: Gad A gene expression is found in the bacteria. They have operon structure in which regulatory,…
Q: What properties demonstrate that the lac repressor is a protein?Describe the evidence that it indeed…
A: Lac operon is negatively regulated by repressor protein.
Q: The lac operon produces enzymes that allow the bacteria E. coli to metabolize lactose, it is in an…
A: Operon is a bacterial and viral genetic regulation mechanism in which genes coding for functionally…
Q: There is a mutation in sequence of the lac operator that prevents the lac repressor from being able…
A: Gene expression is regulated at the level of transcription by operon systems. In prokaryotes,…
Q: Why do scientists define the trp operon as repressible and the lac operon as inducible?
A: Operon is a combination of genes that are transcribed by the same promoter.
Q: How do we know that the orientation of promoters relative to the transcription start site is…
A: Transcription is a process in which a sequence of DNA is transcribed into mRNA.
Q: If you made a mutation in the operator region of the lac promoter such that LacI can no longer bind…
A: Lac operon Lac operon or lactose operon is a negatively regulated operon containing operator gene,…
Q: The figure above shows the structure of lac operon. Which of the following BEST describes what…
A: These are the operon gene found in prokaryotes and the lac operon is an inducible operon.
Lac operon is a transcriptional regulation of lactose metabolism seen in prokaryotes. It was established by the pioneering work of Jacques Monod and François Jacob.
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- For some time, it was not clear whether lac repressor inhibits lac operon transcription by inhibiting the binding of RNA polymerase to its promoter or by allowing transcription initiation but blocking elongation past the site of bound repressor. How might you distinguish between these possibilities?Mechanisms that inhibit TE activity include theproduction of transposition repressors throughalternative splicing and the action of _________ thatblock TE transcription.Many transcriptional activators are proteins with a DNA-binding domain (DBD) and an activation domain (AD). Explain how each domain contributes to transcriptional initiation. Would you expect repressors to also have each of these domains?
- How does the binding of the trp corepressor and the lac inducer to their respective repressor proteins alter repressor function and transcription in each case? What if there was a mutation in the operator region of the lac operon and the active repressor could not bind there? How would this affect the cell’s production of β–galactosidase? In general, Histone acetylation makes DNA ___________________, while DNA methylation makes DNA ________________.Some compounds called antiinducers bind to repressors such as the lac repressor and inhibit the action of inducers; that is, transcription is repressed and higher concentrations of inducer are required to induce transcription. Propose a mechanism of action for anti-inducers.Mutations in bacterial promoters may increase or decrease therate of gene transcription. Promoter mutations that increasetranscription are termed up-promoter mutations, and those thatdecrease transcription are termed down-promoter mutations.The sequence of the −10 site of the promoter for the lac operonis TATGTT (see Figure 14.5). Would you expect each of thefollowing mutations to be an up-promoter or down-promotermutation?A. TATGTT to TATATTB. TATGTT to TTTGTTC. TATGTT to TATGAT
- Suppose that a new mutation lacIes, ('es' stands for ‘extra-strength’) has been discovered in the lac operon that allows the lac-repressor to bind even to the lacOc operator. Other properties of lacIes repressor remain normal (that is the same as of lacI+). Given this genotype Is P+ Oc Z+ Y- / Ies P+ O+ Z+ Y+ , under which conditions will the gene lacZ be transcribed to produce β-galactosidase and the gene lacY transcribed to produce permease? A) With lactose, β-galactosidase and permease are produced, without lactose they are not produced B) With lactose, β-galactosidase is produced, without lactose it is not; permease is never produced C) β-galactosidase is always produced and permease is never produced D) With lactose, β-galactosidase and permease are produced, without lactose they are also produced E) β-galactosidase is always produced and permease is produced only in the presence of lactose. An interesting mutation in lacI results in repressorswith 110-fold increased binding to both operator andnonoperator DNA. These repressors display a “reverse”induction curve, allowing β-galactosidase synthesis inthe absence of an inducer (IPTG) but partly repressingβ-galactosidase expression in the presence of IPTG. Howcan you explain this? (Note that, when IPTG binds a repressor, it does not completely destroy operator affinity,but rather it reduces affinity 110-fold. Additionally, ascells divide and new operators are generated by thesynthesis of daughter strands, the repressor must findthe new operators by searching along the DNA, rapidlybinding to nonoperator sequences and dissociating fromthem.)Compare and contrast the transcriptional regulation of GAL genes in yeast with that of the lac genes in bacteria.
- You have isolated two different mutants (reg1 andreg2) causing constitutive expression of the emu operon (emu1 emu2). One mutant contains a defect in aDNA-binding site, and the other has a loss-of-functiondefect in the gene encoding a protein that binds tothe site.a. Is the DNA-binding protein a positive or negativeregulator of gene expression?b. To determine which mutant has a defect in the siteand which one has a mutation in the binding protein, you decide to do an analysis using F′ plasmids. Assuming you can assay levels of the Emu1and Emu2 proteins, what results do you predict forthe two strains (i and ii; see descriptions below) ifreg2 encodes the regulatory protein and reg1 is theregulatory site?i. F′ (reg1−reg2+emu1−emu2+)/reg1+reg2+emu1+emu2−ii. F′ (reg1+reg2−emu1−emu2+)/reg1+reg2+emu1+emu2−c. What results do you predict for the two strains(i and ii) if reg1 encodes the regulatory proteinand reg2 is the regulatory site?Describe the binding of RNA polymerase, repressors, andactivators to the lac operon when both lactose and glucose are scarce. What is the effect of these scarcities ontranscription of the lac operon?Explain how the data shown indicate that two operator sites are necessary for repression of the lac operon. What would the results have been if all three operator sites were required for the binding of lac repressor?