6) E. coli can use the permease encoded by Lacy to take up the sugar raffinose, however raffinose does not act as an inducer of the lac operon therefore wildtype E. coli cannot grow on raffinose in the absence of lactose because the levels of permease are too low. Genotype I-0+Z+Y•A* I-0+Z*Y*A*/F I+ I-OCZ+Y*A*/F I+ I*0*Z+Y*A*/F 0c ISO*Z*Y*A*/FI+ a) Of the bacterial strains listed in the table (right) which would be able to grow on raffinose in the absence of lactose. Briefly explain/diagram.

6) E. coli can use the permease encoded by Lacy to take up the sugar raffinose, however raffinose does not act as an inducer of the lac operon therefore wildtype E. coli cannot grow on raffinose in the absence of lactose because the levels of permease are too low. Genotype I-0+Z+Y•A* I-0+ZYA/F I+ I-OCZ+YA/F I+ I0Z+YA/F 0c ISOZYA*/FI+ a) Of the bacterial strains listed in the table (right) which would be able to grow on raffinose in the absence of lactose. Briefly explain/diagram.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter13: An Introduction To Genetic Technology

Section: Chapter Questions

Problem 20QP: Analyzing Cloned Sequences A base change (A to T) is the mutational event that created the mutant...

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. 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
Strain X-23 has a mutation in the lacI gene resulting in a lacI protein that cannot bind DNA. Otherwise all other parts of the operon are functional. Circle the least number of components for an F' plasmid that will restore normal regulation and function of the lacoperon in the resulting partial diploid. (may need more than one) (a) lacI+ (b) lacO+ (c) lacP+ (d) lacZ+ (e) None, cannot be restored
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. − + − +
Strain ROFL4 has a premature stop mutation in the lacZ gene, resulting in a nonfunctional b-galactosidase. Otherwise all other parts of the operon are functional. Circle the least number of components for an F' plasmid that will restore normal regulation and function of the lac operon in the resulting partial diploid. (may need more than one) (a) lacI+   (b) lacO+   (c) lacP+   (d) lacZ+   (e) None, cannot be restored.
The map of the lac operon is shown below. Consider the following examples that include both haploids and partial diploids and explain in each scenario whether the repressor can bind and regulate expression and whether or not the lac operon is expressed. For partial diploids the plasmid is indicated by the F’. I+ O+ Z+ Y+ / F’ I+ O+ Z+ Y+   I- O+ Z+ Y+ / F’ I+ O+ Z+ Y+   I- O+ Z+ Y+    I+ Oc Z+ Y+
Strain P77 has a mutation in the lacO that prevents it from being bound by the lacI protein. Otherwise all other parts of the operon are functional. Circle the least number of components for an F' plasmid that will restore normal regulation and function of the lacoperon in the resulting partial diploid. (may need more than one) (a) lacI+   (b) lacO+   (c) lacP+   (d) lacZ+   (e) None, cannot be restored.
In a bacterial cell with the genotype I-: P+: O+: Z+: Y+: A+, which of the following expression patterns of the lac operon would you see? (All + signs designate functional units and - signs designate non-functional units) A. No expression of Z, Y and A under any environmental conditions. B. Z, Y and A would always be expressed. C. Z, Y and A would be expressed when lactose was present but not expressed if lactose is not present. D. Z, Y and A would be expressed in the absence of lactose, but not when lactose was present. E. None of the above.
Strain LOLZ has a mutation in the lacI gene that results in a lacI protein that cannot bind allolactose. Otherwise all other parts of the operon are functional. Circle the least number of components for an F' plasmid that will restore normal regulation and function of the lac operon in the resulting partial diploid. (may need more than one) (a) lacI+ (b) lacO+ (c) lacP+ (d) lacZ+ (e) None, cannot be restored.
For each of the E. coli strains containing lac operon alleles listed, indicate whether the strain is inducible, constitutive, or unable to express beta-galactosidase and permease. (P+ and P- are functional and nonfunctional promoters, respectively) I+ P+ o+ Z- Y+ / I+ P+ oc Z+ Y+ I+ P+ o+ Z+ Y+ / I- P+ oc Z+ Y- I+ P+ o+ Z- Y+ / I- P+ oc Z+ Y- I- P- o+ Z+ Y- / I+ P+ oc Z- Y+ IS P+ o+ Z+ Y+ / I- P+ o+ Z+ Y-
The following shows the genotype of a partial diploid bacterial cell - where one chromosomal region containing the lac operon in E,coli is given, and the other fragment is from a plasmid carrying another lac operon from another source. The two are separated by a slash (/). The possible answers indicate with a ʺ+ʺ or a ʺ-ʺ whether β-galactosidase would be expected to be produced at induced levels under two circumstances: 1) first in the absence of lactose and 2) second in the presence of lactose. (Assume that glucose is not present in the medium.)Genotype F: I+ Oc Z-/ Fʹ I- O+ Z+ KEY:I+ = wild-type repressorI- = mutant repressor (unable to bind to the operator)Is = mutant repressor (insensitive to lactose)O+ = wild-type operatorOc = constitutive operator (insensitive to repressor)
A haploid E. coli cell has the genotype I ¯ P+ O+ Z+ Y ¯ where the I ¯ indicates that the repressor protein cannot bind to the operator due to a mutation. Which of the following statements about cells with this lac operon genotype are correct? I ¯ P+ O+ Z+ Y ¯ Select all that apply. β-galactosidase will be transcribed constitutively. The cells are able to import lactose across the cell membrane. The cells are lac+ and are able to grow on a medium with lactose but no glucose. RNA polymerase can bind to the promoter.
A partial diploid in E. coli is created so that LacI is no longer expressed from the genome and is instead expressed from a plasmid. When this E. coli strain is grown in the presence of lactose and glucose, we should expect that the lac operon will be: Question 14 options: Constitutively expressed due to LacI being expressed from a plasmid Induced due to functional Catabolite Activator Protein (CAP) Repressed due to functional LacI Induced due to non-functional LacI Expressed at low levels due to non-functional Catabolite Activator Protein (CAP)