Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Textbook Question
Chapter 6, Problem 7PDQ
Why are the recombinants produced from an Hfr × F− cross rarely, if ever, F+?
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DNA obtalned from the indicated donor strains is used to TRANSFORM the indicated recipient strains. The resulting progeny are plated on minimal medium so that only wild-
type recombinants are scored. The number of wild-types for each cross is given in the chart below. What is the order of the genes?
Donor
Recipient
wid type colonies
a-b- c+
a+ b+ c-
273
a- b+ c-
a+ b-c+
462
a- b+ C+
a+ b-c-
2
a b- C+
a- b+ c+
O 4-b-c
a-o-b
b-a-c
cannot be determined
Question 18 of 26
In E. coli, four Hfr strains donate the following markers,shown in the order donated:Strain 1: M Z X W CStrain 2: L A N C WStrain 3: A L B R UStrain 4: Z M U R BAll these Hfr strains are derived from the same F+ strain.What is the order of these markers on the circularchromosome of the original F+?
From a cross between e+ f+ g+ and e− f − g− strains ofNeurospora, recombination between these linkedgenes resulted in a few octads containing the followingordered set of spores:e+ f+ g+e+ f+ g+e+ f − g+e+ f − g+e− f − g−e− f − g−e− f − g−e− f − g−a. Where was recombination initiated?b. Did crossing-over occur between genes e and g?Explain.c. Why do you end up with 2 f+ : 6 f − but 4 e+: 4 e−and 4g+: 4g−?d. Could you characterize these unusual octads as MIor MII for any of the three genes involved?Explain.
Chapter 6 Solutions
Concepts of Genetics (12th Edition)
Ch. 6 - When the interrupted mating technique was used...Ch. 6 - In a transformation experiment involving a...Ch. 6 - In complementation studies of the rII locus of...Ch. 6 - A 4-month-old infant had been running a moderate...Ch. 6 - Prob. 2CSCh. 6 - Prob. 3CSCh. 6 - Prob. 4CSCh. 6 - HOW DO WE KNOW? In this chapter, we have focused...Ch. 6 - Review the Chapter Concepts list on p. 123. Many...Ch. 6 - With respect to F+ and F bacterial matings, answer...
Ch. 6 - List all major differences between (a) the F+ F...Ch. 6 - Describe the basis for chromosome mapping in the...Ch. 6 - In general, when recombination experiments are...Ch. 6 - Why are the recombinants produced from an Hfr F...Ch. 6 - Describe the origin of F bacteria and merozygotes.Ch. 6 - In a transformation experiment, donor DNA was...Ch. 6 - Describe the role of heteroduplex formation during...Ch. 6 - Explain the observations that led Zinder and...Ch. 6 - Prob. 12PDQCh. 6 - Two theoretical genetic strains of a virus (abc...Ch. 6 - The bacteriophage genome consists of many genes...Ch. 6 - If a single bacteriophage infects one E. coli cell...Ch. 6 - A phage-infected bacterial culture was subjected...Ch. 6 - In recombination studies of the rII locus in phage...Ch. 6 - In an analysis of rII mutants, complementation...Ch. 6 - If further testing of the mutations in Problem 18...Ch. 6 - Using mutants 2 and 3 from Problem 19, following...Ch. 6 - During the analysis of seven rII mutations in...Ch. 6 - In studies of recombination between mutants 1 and...Ch. 6 - Prob. 23ESPCh. 6 - An Hfr strain is used to map three genes in an...Ch. 6 - A plaque assay is performed beginning with 1 mL of...Ch. 6 - In a cotransformation experiment, using various...Ch. 6 - For the experiment in Problem 26, another gene, g,...Ch. 6 - Bacterial conjugation, mediated mainly by...Ch. 6 - A study was conducted in an attempt to determine...
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- An Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.What information do you know based on the question and your understanding of the topic?arrow_forwardCalculate the recombination frequencies between r2 and h and between r13 and h.arrow_forwardA cross is made between two E. coli strains: Hfr arg + bio + leu+ × F− arg − bio − leu−. Interrupted mating studies show that arg+ enters the recipient last, and so arg+ recombinants are selected on a medium containing bio and leu only. These recombinants are tested for the presence of bio + and leu+. The following numbers of individuals are found for each genotype: arg+ bio+ leu+ 320 arg+ bio- leu+ 0 arg+ bio+ leu- 8 arg+ bio- leu- 48a. What is the gene order? b. What are the map distances in recombination percentages?arrow_forward
- the circled answer is wrong.arrow_forwardA bacterial strain with genotype his− leu− thr− is transformed with DNA from a strain that is his+ leu+ thr+. A few leu+ thr+ cells and a few his+ thr+ cells are found, but no his+ leu+ cells are observed. Which genes are farthest apart?arrow_forwardDraw all possible linkage maps for these three genes.arrow_forward
- An Hfrstrain that is a *b*c*d* e*f* g *h* is mated with an F strain that is a b e d e f gh. The mating is interrupted at 5 minutes interval, and the genotypes of the F recombinants are determined. The results obtained are tabulated in Table 2. Draw the map of the Hfrchromosome and indicate the position of the origin of transfer, the direction of the transfer and the minutes between genes. Table 2:Entry time of Hfr chromosome into recipient cell. Time a d e f h 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +arrow_forwardAn Hfr strain that is leuA+ and thiL+ was mixed with a strain thatis leuA− and thiL−. In the data points shown in the following graph,the conjugation was interrupted at different time points, and thepercentage of recombinants for each gene was determined bystreaking on a medium that lacked either leucine or thiamine.Make a calculation.arrow_forwardAn Hfr strain that is lacZ" and galE" was mated to a strain that is lacZ and galE. The mating was interrupted and the percentage of recombinants for each gene was determined by streaking on plates that contain either lactose or galactose as the sole carbon source. The following results were obtained: 30- lacz 20 10- galE 01 10 16 20 25 30 40 50 Duration of mating (minutes) (i) Determine the map distance (in minutes) between these two genes. In a previous experiment, it was found that lacZ is 6 minutes away from gene hisB. galE was shown to be 15 minutes from this gene. Draw a genetic map describing the locations of all three genes. (ii) % of F recipient cells that have received the gene during conjugationarrow_forward
- A particular Hfr strain normally transmits the pro+marker as the last one in conjugation. In a cross of thisstrain with an F− strain, some pro+ recombinants are recovered early in the mating process. When these pro+cells are mixed with F−cells, the majority of the F− cellsare converted into pro+ cells that also carry the F factor.Explain these results.arrow_forwardWhen the interrupted mating technique was used withfive different strains of Hfr bacteria, the following orders ofgene entry and recombination were observed. On the basisof these data, draw a map of the bacterial chromosome.Do the data support the concept of circularity?HfrStrain Order1 T C H R O2 H R O M B3 M O R H C4 M B A K T5 C T K A Barrow_forwardIn a transformation experiment, donor DNA was obtained from a prototroph bacterial strain (x* y z'), and the recipient was a triple auxotroph (x y z ). The following transformant classes were obtained: x* y z xy'z 160 130 190 170 x'y 3 xy x'y 5 What general conclusions can you draw about the linkage relationships among the three genes?arrow_forward
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