Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 14, Problem 3EQ
As described in experimental question E2 and also in Chapter 21, the technique of Northern blotting can be used to detect the level of transcription of a specific RNA. Draw the results you would expect from a Northern blot if bacteria were grown in media that contained lactose (and no glucose) but had the following mutations:
A. Lane 1. Normal strain
B. Lane 2. Strain with a mutation that inactivates lac repressor
C. Lane 3. Strain with a mutation that prevents allolactose from binding to lac repressor
D. Lane 4. Strain with a mutation that inactivates CAP
How would your results differ if these bacterial strains were grown in media that did not contain lactose or glucose?
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Students have asked these similar questions
A number of mutations affect the expression of the lac operon in E. coli. The
genotypes of several E. coli strains are shown below. ("+" indicates a wild-type gene
with normal function and "-" indicates a loss-of-function allele.) Please predict which
of the following strains would have the highest beta-galactosidase enzyme activity,
when grown in the lactose medium.
O CAP+ r* p* o* z
O CAP* I P* o* z*
O CAP* r* P O* z*
O CAP I P* O z*
A sample of E.coli cells is transformed with a plasmid containing a transcriptional fusion including the
promoter of an E.coli housekeeping gene and the LacZ gene. The transformed cells are plated out on
selective medium containing X-gal. Which of the following best describes the likely results.
a. Colonies will only be blue if lactose is also included in the growth medium.
b. Colonies will only be blue if lactose and glucose are included in the growth medium
c. Most of the colonies should turn blue.
d. Presence of any white colonies may indicate deletion or mutation of the promoter.
e. Both c. and d. are correct
You are working with a laboratory strain of E.coli that contains a 10 base-pair
deletion in the Lac operator region.
You grow this mutated strain of E.coli in a variety of media conditions as shown
below for two hours. After two hours you are able to measure the amount of beta-
galactosidase activity (from the lacZ gene product) in each cell culture.
Media condition
A
C
High lactose, high glucose 100 units
100 units
100,000 units
100 units
High lactose, no glucose
100 units
100,000 units
100 units
100,000 units
No lactose, no glucose
100 units
100J000 units
100 units
100 units
No lactose, high glucose
100 units
100 units
100,000 units
100 units
Which column best represents the data you would expect with a wild-type or normal
strain?
A
C
Chapter 14 Solutions
Genetics: Analysis and Principles
Ch. 14.1 - 1. A repressor is a __________ that _________...Ch. 14.1 - 2. Which of the following combinations will cause...Ch. 14.2 - 1. What is an operon?
a. A site in the DNA where...Ch. 14.2 - The binding of _______ to lac repressor causes lac...Ch. 14.2 - Prob. 3COMQCh. 14.2 - How does exposing an E. coli cell to glucose...Ch. 14.3 - When tryptophan binds to trp repressor, this...Ch. 14.3 - During attenuation, when tryptophan levels are...Ch. 14.3 - Operons involved with the biosynthesis of...Ch. 14.4 - 1. Translation can be regulated by
a....
Ch. 14.4 - Prob. 2COMQCh. 14.5 - 1. For a riboswitch that controls transcription,...Ch. 14 - 1. What is the difference between a constitutive...Ch. 14 - In general, why is it important to regulate genes?...Ch. 14 - Prob. 3CONQCh. 14 - Transcriptional regulation often involves a...Ch. 14 - An operon is repressible-a small effector molecule...Ch. 14 - Prob. 6CONQCh. 14 - 7. What is enzyme adaptation? From a genetic point...Ch. 14 - Prob. 8CONQCh. 14 - Prob. 9CONQCh. 14 - Prob. 10CONQCh. 14 - Mutations may have an effect on the expression of...Ch. 14 - 12. Would a mutation that inactivated lac...Ch. 14 - Prob. 13CONQCh. 14 - 14. As shown in Figure 14.12, four regions within...Ch. 14 - 15. As described in Chapter 13, enzymes known as...Ch. 14 - 16. The combination of a 3–4 stem-loop and a...Ch. 14 - 17. Mutations in tRNA genes can create tRNAs that...Ch. 14 - Prob. 18CONQCh. 14 - Prob. 19CONQCh. 14 - A species of bacteria can synthesize the amino...Ch. 14 - 21. Using three examples, describe how allosteric...Ch. 14 - How are the actions of lac repressor and trp...Ch. 14 - 23. Transcriptional repressor proteins (e.g., lac...Ch. 14 - Answer the following questions that pertain to the...Ch. 14 - Chapter 21 describes a blotting method known as...Ch. 14 - As described in experimental question E2 and also...Ch. 14 - Prob. 4EQCh. 14 - Explain how the data shown in Figure 14.9 indicate...Ch. 14 - Prob. 6EQCh. 14 - Lets suppose you have isolated a mutant strain of...Ch. 14 - Prob. 1QSDCCh. 14 - Prob. 2QSDC
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- The following table lists 4 bacterial strains that are partial diploids for lac operon genes. Given the activity of beta-galactosidase measured for each strain in the absence (-lac) or presence (+lac) of lactose, complete the table by choosing the appropriate symbol (+, -, C, S) to indicate the allele of the gene or site missing from the table (blue numbers). strain A BC 5 C D 7 chromosome I O 1 2 4 1 [Select] 9 3 [Select] [Select] [Select] 9 [Select] + + Z + + 6 + I +5 + 10 plasmid O 3 + 7 C Z + 8 8 2 [Select] 4 [Select] 6 [Select] B-gal act. -lac +lac 0.002 0.003 0.002 0.058 0.063 0.121 0.059 0.062 Select] 1 ✔ [ Select] + is C Sarrow_forwardA research group is studying a bacterium X that binds to mucosal cells in the lung and invades. Wildtype X has an LD50 value of 10 bacteria when administered to mice by inhalation. Using transposon mutagenesis, the researchers have isolated two mutants of X that they call Xmut1 and Xmut2, both of which have LD50 values of 105 when inhaled by mice. However, in tissue culture cells, Xmut1 can invade the cells just as well as wild-type X, while Xmut2 cannot. Provide a possible explanation for these results.arrow_forwardYou are working with a laboratory strain of E.coli that contains a 10 base-pair deletion in the Lac operator region. You grow this mutated strain of E.coli in a variety of media conditions as shown below for two hours. After two hours you are able to measure the amount of beta- galactosidase activity (from the lacZ gene product) in each cell culture. Media condition А В C High lactose, high glucose 100 units 100 units 100,000 units 100 units High lactose, no glucose 100 units 100,000 units 100 units 100,000 units No lactose, no glucose 100 units 100,000 units 100 units 100 units No lactose, high glucose 100 units 100 units 100,000 units 100 units Which column best represents the data you would expect with this mutated strain? C OA ODarrow_forward
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- A number of mutations affect the expression of the lac operon in E. coli. The genotypes of several E. coli strains are shown below. ("+" indicates a wild-type gene with normal function and "-" indicates a loss-of-function allele.) Please predict which of the following strains would have the lowest beta-galactosidase enzyme activity, when grown in the lactose medium. OF POZY Ort Ptot Z¹ Yt Ort p²o+z¹Y+ Orpt ot ztyarrow_forwardExplain how the lac operon can be used to express a recombinant protein in an E. coli cell. Explain why the B-galactosidase gene is made in two pieces with the a and 2 parts of the enzyme.arrow_forwardThe 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)arrow_forward
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