The inducible galactose operon of E. coli has three co-transcribed genes (galk, galE, galT) encoding the kinase enzyme, epimerase enzyme, and transferase enzyme, respectively. You have isolated an interesting regulatory mutant, galX¯, with the phenotype shown in the second row of the following table. A means enzyme absent; P means enzyme present. without galactose with galactose genotype kinase transferase kinase transferase wildtype A A P P galx P P P P What is the role of the galX gene? [Select] The phenotype of a galX mutant is an example of [Select] To determine if the galX gene encodes a regulatory protein or serves as a regulatory site, you make a partial diploid with the following genotype: galX galK+ galT/ galX galK galT+ Complete the table below by assigning to each number in blue either A or P to indicate the enzyme phenotype expected if galX encodes a protein or serves as a site. without galactose with galactose kinase transferase kinase transferase as site 1 2 3 4 as protein 5 6 7 8 1 [Select] 2 [Select] 3 [ Select] 4 [Select] 5 [Select] 6 [Select] 7 [Select] 8 [Select]

The inducible galactose operon of E. coli has three co-transcribed genes (galk, galE, galT) encoding the kinase enzyme, epimerase enzyme, and transferase enzyme, respectively. You have isolated an interesting regulatory mutant, galX¯, with the phenotype shown in the second row of the following table. A means enzyme absent; P means enzyme present. without galactose with galactose genotype kinase transferase kinase transferase wildtype A A P P galx P P P P What is the role of the galX gene? [Select] The phenotype of a galX mutant is an example of [Select] To determine if the galX gene encodes a regulatory protein or serves as a regulatory site, you make a partial diploid with the following genotype: galX galK+ galT/ galX galK galT+ Complete the table below by assigning to each number in blue either A or P to indicate the enzyme phenotype expected if galX encodes a protein or serves as a site. without galactose with galactose kinase transferase kinase transferase as site 1 2 3 4 as protein 5 6 7 8 1 [Select] 2 [Select] 3 [ Select] 4 [Select] 5 [Select] 6 [Select] 7 [Select] 8 [Select]

Name: The inducible galactose operon of E. coli has three co-transcribed ge
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Description: The inducible galactose operon of E. coli has three co-transcribed genes (galK, galE, galT) encodingthe kinase enzyme, epimerase enzyme, and transferase enzyme, respectively. You have isolated aninteresting regulatory mutant, galX, with the phenotyp

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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In the galactose operon of Escherichia coli, a repressor, encoded by the galR gene, binds to an operator site, galo, to regulate the expression of three structural genes, galE, galT, and galK. Expression is induced by the presence of galactose in the media. For each of the strains listed, would the cell show constitutive, inducible, or no expression of each of the structural genes? (Assume that galR−is a loss-of-function mutation.) galR− galo+ galE+ galT+ galK+ galR+ galoc galE+ galT+ galK+ galR− galo+ galE+ galT+ galK−/ galR+ galo+ galE− galT+ galK+ galR− galoc galE+ galT+ galK−/ galR+ galo+ galE− galT+ galK+
You have isolated two different mutants (reg1 and reg2) causing constitutive expression of the emu operon (emu1 emu2). One mutant contains a defect in a DNA-binding site, and the other has a loss-of-function defect in the gene encoding a protein that binds to the site. Is the DNA-binding protein a positive or negative regulator of gene expression? Explain. To determine which mutant has a defect in the site and 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 Emu1 and Emu2 proteins, what results do you predict for the two strains (i and ii; see descriptions below) if reg2 encodes the regulatory protein and reg1 is the regulatory site? Explain. F′ (reg1− reg2+ emu1− emu2+)/reg1+ reg2+ emu1+ emu2− F′ (reg1+ reg2− emu1− emu2+)/reg1+ reg2+ emu1+ emu2−
Suppose you have six strains of E. coli. One is wildtype, and each of the other five has a single one of thefollowing mutations: lacZ−, lacY−, lacI−, oc, andlacIS. For each of these six strains, describe thephenotype you would observe using the following assays. [Notes: (1) IPTG is a colorless synthetic molecule that acts as an inducer of lac operon expressionbut cannot serve as a carbon source for bacterialgrowth because it cannot be cleaved byβ-galactosidase; (2) X-gal cannot serve as a carbonsource for growth; (3) E. coli requires active lactosepermease (the product of lacY) to allow lactose,X-gal, or IPTG into the cells.] Colony color in medium containing glycerol as theonly carbon source and X-gal, but no IPTG.d. Colony color in medium containing high levels ofglucose as the only carbon source, X-gal, andIPTG.e. Colony color in medium containing high levels ofglucose as the only carbon source and X-gal, butno IPTG
. Suppose you have six strains of E. coli. One is wildtype, and each of the other five has a single one of thefollowing mutations: lacZ−, lacY−, lacI−, oc, andlacIS. For each of these six strains, describe thephenotype you would observe using the following assays. [Notes: (1) IPTG is a colorless synthetic molecule that acts as an inducer of lac operon expressionbut cannot serve as a carbon source for bacterialgrowth because it cannot be cleaved byβ-galactosidase; (2) X-gal cannot serve as a carbonsource for growth; (3) E. coli requires active lactosepermease (the product of lacY) to allow lactose,X-gal, or IPTG into the cells.]a. Growth on medium in which the only carbonsource was lactose.b. Colony color in medium containing glycerol as theonly carbon source, X-gal, and IPTG
Two closely linked open reading frames (ORFs) have been identified on the E. coli chromosome and they are predicted to encode genes sugX sugY which is involved in the catabolism (utilization) of a non-glucose sugar. In the figure below, the top line (with the big arrow) is the coding strand, and the bottom line is the non-coding (template) strand of the operon. Since the RNA sequence would be the “same” as the coding strand, please label (show the location of), in relation to the ORFs, the promoter(s) and 4 other genetic elements in this region that may be involved in the transcription and translation of sugX and sugY as well as the regulation of their expression. (Note: genetic elements are the regions of DNA or RNA.) If you are not comfortable with the coding strand of the DNA, feel free to draw the mRNA strand underneath and label the relevant features on the RNA strand, but the RNA strand must be aligned with the DNA strands in position and scale. Leader(s)/antileader(s) and…
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?
Give all possible genotypes of a lac operon that produces, or fails to produce, β-galactosidase and permease under the following conditions. Do not give partial-diploid genotypes. Lactose absent Lactose present β-Galactosidase Permease β-Galactosidase Permease a. − − + + b. − − − + c. − − + − d. + + + + e. − − − − f. + − + − g. − + − +
Give the levels of Beta-galactosidase activity (high or low or zero) expected for the following partial diploids for the lac operon strains.
Arginine is one of the amino acids that serves as a building block for protein synthesis. Arginine biosynthesis depends on the expression of the arg operon, which encodes ArgC (a reductase) and ArgB (acetylglutamate kinase). Which of the following statements regarding mutation of the arginine biosynthesis repressor ArgR is true? O A 1-bp insertion in the argR gene would result in a mutant able to grow in the absence of arginine, O A 1-bp deletion in the argB gene would result in a mutant unable to transcriptionally regulate the arg operon encoding argB. O A 1bp insertion in the argC gene would result in a mutant able to grow in the absence of arginine. O A 1-bp deletion in the argR gene would result in a mutant that represses the arg operon when grown in the presence of arginine. None of the above.
In addition to observing similarities to the lac operon, you also notice that this gene is regulated via attenuation, similar to the trp operon. Based on this similarity to this model operon, you could state that ___________. Group of answer choices If a terminator loop forms in the DNA, the expression of the structural genes is halted. The formation of the terminator hairpin followed by a series of Uracil (UUUUUUU) functions similar to Rho-Independent termination to result in the stopping of transcription. The transcription of a leader sequence affects the translation of the structural genes. Never mind – all of these statements are true! Attenuation will be the primary means of transcriptional regulation, with a repressor used as a back up option.
You have isolated different mutants (reg1 and reg2) causing constitutive expression of the emu operon (which has genes emu1 and emu2). One mutant contains a defect in a DNA-binding site, and the other has a loss-of-function defect in the gene encoding a protein that binds to the site. Is the DNA-binding protein a positive or negative regulator of gene expression?
The symbols A, B, C, D, E represent all the components of the lac operon, excluding LacA. The symbols are not in the order of the lac operon. Minus and plus signs represent activity of lacZ or LacY in the absence or presence of IPTG. LacI+ or LacI-, and LacO+ or LacOC alleles were used. Which of the symbols represents each of the lac operon components?