Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
3rd Edition
ISBN: 9780135564172
Author: Mark Sanders, John Bowman
Publisher: PEARSON+
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Textbook Question
Chapter 12, Problem 33P
The following hypothetical genotypes have genes A, B, and C corresponding to lacI,lacO, andlacZ but not necessarily in that order. Data in the table indicate whether
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The lac genotypes are as shown below:
P+OcZ-Y+A+// P¯O+Z+Y+A+
(i)
The lac operon consists of three structural genes, lacZ, lacY and lacA. Which
structural genes are involved in lactose metabolism? Explain.
(ii)
Draw and explain how lactose repress the gene expression in lac IS/I- heterozygote.
(iii)
What is the function of the promoter in the bacterial operon?
After irradiating wild-type cells of Neurospora (a haploid fungus), a geneticist finds two leucine-requiringauxotrophic mutants. He combines the two mutants ina heterokaryon and discovers that the heterokaryon isprototrophic.a. Were the mutations in the two auxotrophs in the samegene in the pathway for synthesizing leucine or in twodifferent genes in that pathway? Explain.b. Write the genotype of the two strains according toyour model.c. What progeny and in what proportions would youpredict from crossing the two auxotrophic mutants?(Assume independent assortment.)
For the genotypes and conditions (lactose present or absent) shown in the following Table 2,
predict whether the expression of beta-galactosidase is inducible (I), noninducible (N) or
constitutive (C). Explain your reason.
Table 2
Genotype
I*p*o°z+
Condition
(i)
No lactose
(ii)
(iii)
(iv)
I*P*O*Z+
I*P•O*Z*
I$P*O°Z*
Lactose
Lactose
Lactose
(v)
IP*0°Z+
No lactose
Chapter 12 Solutions
Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
Ch. 12 - 12.1 Bacterial genomes frequently contain groups...Ch. 12 - Transcriptional regulation of operon gene...Ch. 12 - Why is it essential that bacterial cells be able...Ch. 12 - Identify similarities and differences between an...Ch. 12 - The transcription of -galactosidase and permease...Ch. 12 - 12.6 Is attenuation the product of an allosteric...Ch. 12 - The trpL region contains four repeated DNA...Ch. 12 - The CAP binding site in the lac promoter is the...Ch. 12 - What role does cAMP play in transcription of lac...Ch. 12 - How would a cap- mutation that produces an...
Ch. 12 - Explain the circumstances under which attenuation...Ch. 12 - Consider the transcription of genes of the...Ch. 12 - Describe the lytic and lysogenic life cycles of ...Ch. 12 - 12.14 Define antisense RNA, and describe how it...Ch. 12 - 12.15 Attenuation of trp operon transcription is...Ch. 12 - 12.16 In the lac operon, what are the likely...Ch. 12 - Identify which of the following lac operon haploid...Ch. 12 - Prob. 18PCh. 12 - 12.19 List possible genotypes for lac operon...Ch. 12 - Suppose each of the genotypes you listed in parts...Ch. 12 - 12.21 Four independent mutants (mutants A to D)...Ch. 12 - Suppose the lac operon partial diploid...Ch. 12 - What is a riboswitch? Describe the riboswitch...Ch. 12 - 12.24 A repressible operon system, like the trp...Ch. 12 - 12.25 What is the likely effect of each of the...Ch. 12 - 12.26 Suppose that base substitution mutations...Ch. 12 - 12.27 Two different mutations affect. Mutant...Ch. 12 - How would mutations that inactivate each of the...Ch. 12 - The bacterial insertion sequence IS 10 uses...Ch. 12 - For an E. coli strain with the lac operongenotype...Ch. 12 - 12.31 How could antisense RNA be used as an...Ch. 12 - 12.32 Section describes the function of tRNA...Ch. 12 - The following hypothetical genotypes have genes A,...Ch. 12 - 12.34 Northern blot analysis is performed on...Ch. 12 - Prob. 35PCh. 12 - Prob. 36PCh. 12 - 12.37 The electrophoresis gel shown in part (a) is...
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- Why is it adaptive for the structural genes for using lactose to be under the control of a single promoter (i.e., synthesize a polycistronic message rather than three monocistronic messages)? a. For efficient absorption and catabolism of lactose, structural genes send a single signal. This is why polycistronic message is favored more than the monocistronic message since the former involves transmission of numerous messages in initiation and termination. b. Polycistronic message is favored more than the monocistronic message. c. Polycistronic message is favored more than the monocistronic message since the former involves transmission of numerous messages in initiation and termination. d. For an efficient absorption and catabolism of lactose, structural genes send a single signal only. e. Polycistronic message is favored more than the monocistronic message since the former involves transmission of single message in initiation and termination.arrow_forwardSearching the yeast Saccharomyces cerevisiae genome, researchers found approximately 4,000 DNA sites with a sequence which could potentially bind the yeast transcription factor GAL4. GAL4 activates the transcription of galactose genes. Yet there are only 10 GAL4-binding sites which control the genes necessary for galactose metabolism. The GAL4 binding sequence is CGGAT#AGAAGC*GCCG, where # is T, C or G, and * is C or T. In one chromatin immunoprecipitation experiment (ChIP), yeast growing on galactose were lysed, and subjected to cross-linking reagents which cross-linked transcription factors and activators to DNA. Next the DNA was sheared into small fragments, and antibodies to GAL4 were added. These antibodies coprecipitated the GAL4 and the DNA it was cross-linked to. The cross-linking was then chemically reversed, and the DNA was isolated, cloned into a library of plasmids and sequenced. Results showed that only 10 different DNA sequences had GAL4 bound. Since the…arrow_forwardScientists studied gene expression and phenotypes of the YJL213W gene in yeast to determine how phosphate was transported based on two different genotypes. The PHO84 locus of the gene is a phosphate transporter and the PHO4 locus is a regulator of genes that respond to phosphate availability. Two genotypes were compared and are shown in the graph: BY (solid black line, triangles) and RM (dashed line, Xs). Which of the following statements describes the correlation between the genotype, phosphate concentration, and YJL213W expression based on the data? A - In RM genotypes, a lower PHO4 activation level led to less YJL213W expression and a lower rate of phosphate transport. B - In RM genotypes, a greater PHO4 activation level led to less YJL213W expression and a lower rate of phosphate transport. C = In BY genotypes, a lower activation level of PHO4 led to more YJL213W expression and a higher rate of phosphate transport. D - In BY genotypes a greater activation level of…arrow_forward
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