Genetic Analysis: An Integrated Approach (2nd Edition)
2nd Edition
ISBN: 9780321948908
Author: Mark F. Sanders, John L. Bowman
Publisher: PEARSON
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Chapter 14, Problem 19P
List possible genotypes for lacoperon haploids that have the following phenotypic characteristics:
a. The operon genes are constitutively transcribed, but the strain is unable to grow on a lactose medium. List two possible genotypes for this
b. The operon genes are never transcribed above a basal level, and the strain is unable to grow on a lactose medium. List two possible genotypes for this phenotype.
c. The operon genes are inducibly transcribed, but the strain is unable to grow on a lactose medium. List one possible genotype for this phenotype.
d. The operon genes are constitutively transcribed, and the strain grows on lactose medium. List two possible genotypes for this phenotype.
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Students have asked these similar questions
The streptolysin S toxin made by S. pyogenes is encoded by a 9-gene
operon, sagABCDEFGHI. Thinking about what a 3-line diagram would look like for this
operon, answer the following questions. Write numeric answers only. For example, if your
answer is 6 promoters, write only 6.
1) How many promoters control the expression of these genes?
2) How many locations does RNA Polymerase bind to get full expression of these genes?
3) How many ribosome binding sites are needed for full protein expression?
4) How many start codons will be needed for full protein expression?
5) How many mRNA strands will be produced with full operon expression?
6) How many proteins will be produced with full protein expression?
1
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 zty
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+
Chapter 14 Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
Ch. 14 - 12.1 Bacterial genomes frequently contain groups...Ch. 14 - Transcriptional regulation of operon gene...Ch. 14 - Why is it essential that bacterial cells be able...Ch. 14 - Identify similarities and differences between an...Ch. 14 - The transcription of -galactosidase and permease...Ch. 14 - 12.6 Is attenuation the product of an allosteric...Ch. 14 - The trpL region contains four repeated DNA...Ch. 14 - The CAP binding site in the lac promoter is the...Ch. 14 - What role does cAMP play in transcription of lac...Ch. 14 - How would a cap- mutation that produces an...
Ch. 14 - Explain the circumstances under which attenuation...Ch. 14 - Consider the transcription of genes of the...Ch. 14 - Describe the lytic and lysogenic life cycles of ...Ch. 14 - 12.14 Define antisense RNA, and describe how it...Ch. 14 - 12.15 Attenuation of trp operon transcription is...Ch. 14 - 12.16 In the lac operon, what are the likely...Ch. 14 - Identify which of the following lac operon haploid...Ch. 14 - Prob. 18PCh. 14 - 12.19 List possible genotypes for lac operon...Ch. 14 - Suppose each of the genotypes you listed in parts...Ch. 14 - 12.21 Four independent mutants (mutants A to D)...Ch. 14 - Suppose the lac operon partial diploid...Ch. 14 - Prob. 23PCh. 14 - 12.24 A repressible operon system, like the trp...Ch. 14 - 12.25 What is the likely effect of each of the...Ch. 14 - 12.26 Suppose that base substitution mutations...Ch. 14 - 12.27 Two different mutations affect. Mutant...Ch. 14 - How would mutations that inactivate each of the...Ch. 14 - The bacterial insertion sequence IS 10 uses...Ch. 14 - 12.34 Northern blot analysis is performed on...Ch. 14 - 12.37 The electrophoresis gel shown in part (a) is...Ch. 14 - Prob. 32PCh. 14 - The following hypothetical genotypes have genes A,...Ch. 14 - For an E. coli strain with the lac operongenotype...
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- A number of mutations affect the expression of the lac operon in E. coli. Consider each genotype below and complete the table using “+” to indicate that the gene is expressed, and “−” to indicate that gene is not expressed.arrow_forwardA strain of E. coli has the genotypes shown below at the lac operon, where I = regulator gene, P = promoter, O = operator, Z = βgalactosidase gene, and Y = permease gene. The superscript+ indicates a wild-type allele,c indicates a constitutive mutation, and− indicates a defective mutation. For each genotype, indicate whether the enzyme will be synthesized or not synthesized when lactose is present or absent by placing a + for synthesis occurring and a − for synthesis not occurring in the appropriate blank. Explain your reasoning for each answer.arrow_forwardA 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. Orpt o* z* r* Orpt ot z* Y OrptoztY Orrotzr OrPotz*Yarrow_forward
- 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)arrow_forwardNonearrow_forwardThe genotypes of five merozygote bacteria are shown below. In each set, the genotype of the lac operon on the chromosome is on the left side of the slash () and the genotype of the lac operon on the F' plasmid is on the right side of the slash. Which of the merozygote bacteria listed below would be able to make high quantities of B-galactosidase in the absence of lactose? Mark all the answers that are correct. O i p*o°z¯ y*A*/F'I$ p*oʻz*y*A* I* p* o*Z¯YA*/F'T P*O*z*y* A* I* P* o*z*Y* A* /F'T P*O*z*y* A* O 1* p*o*z° YA*/F'T P*o°z*y*A* 1S p*0°2¯Y¯AZET P*O*Z*Y*A*arrow_forward
- 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 IPTGarrow_forwardThe lactose operon in E. coli comprises two structural genes and three regulatory components.a.State the name of each structural gene and describe its function: b.) State the name of each regulatory component and describe its functionarrow_forwardGive the levels of Beta-galactosidase activity (high or low or zero) expected for the following partial diploids for the lac operon strains.arrow_forward
- Given the following genotypes, explain, by answering the questions in each number, how the mutation (identified by a (-) superscript) will affect E. coli grown in lactose medium. Will there be a complete set ofgene products? (Yes/No) Will the lac operon be turnedon/off? Will the cell survive? (Yes/No) a. i + p + o + z - y + b. i + p - o + z + y + c. i + p + o - z + y +arrow_forwardGive all possible genotypes of a lac operon that produces, or fails to produce, B-galactosidase and permease under the following conditions. Do not give partial-diploid genotypes. Lactose present B-Galactosidase Lactose absent B-Galactosidase Permease Permease a. b. C. d. e. f. g. + I + II + + + | +Iarrow_forwardParts A-C show the genotypes for partial diploid strains of the lac operon. Gene names have been simplified (ie, LacZ is shown as Z), with alleles shown as standard notations. There are two copies of the operon, one line is the copy in the genome and the other line is on a plasmid. In the blanks, indicate the following based on regulation of the structural gene in the header, choose "functional' if you expect that any amount of normal enzyme will be made, "nonfunctional" if you expect that transcription occurs but the enzyme is mutated, or "no transcription if the structural gene is not transcribed. Assume glucose is absent. LacY Enzyme Activity Genotype of Strain Absence of allolactose I-P+O+Z+Y+ I+P+ O° Z-Y- 1+ P+ OF Z+Y- PP+O+Z-Y+ 1-P+O+Z+Y- I+P-O+Z-Y+ Presence of allolactosearrow_forward
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