Concept explainers
As mentioned in question 2 of More Genetic TIPS, origins of transfer can be located in many different locations, and their direction of transfer can be clockwise or counterclockwise. Let’s suppose a researcher conjugated six different Hfr strains that were
Strain | Order of Gene Transfer |
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Draw a circular map of the E. coli chromosome that shows the locations and orientations of the origins of transfer in these six Hfr strains.
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Genetics: Analysis and Principles
- Three different Hfr donor strains are mixed with separate samples of an F strain, and the following mapping data are provided from studies of interrupted conjugation: Appearance of genes in F cells Hfr1: Genes b* d* c* f* g* Time* 3 16 27 59 Hfr2: Genes e* f* c* d* b+ Time 6 24 35 46 48 Hfr3: Genes d* c* f* e+ g* Time 4 15 26 44 58 Construct a genetic map for these genes, indicating their order on the bacterial chromosome and the distances between them.arrow_forwardThe following two strains of E. coli are crossed with each other: Hfr pan* thi* ala* and F¯pan¯ thi¯ ala¯ It was shown that the pan marker entered last in interrupted conjugation experiments. By spreading the bacteria from these experiments on different selection media, the following results (in number of colonies) were obtained: MM + Gluc IM + Gluc + ala MM + Gluc + thi MM + Gluc + thi + ala 280 281 286 339 Give the number of each phenotypic class and justify your answer. Determine the order of the genes. What are the genetic distances between the different loci? Abbreviations: Gluc: glucose; Ala: alanine; Thi: thiamine; Pan: pantothenic acid.arrow_forwardThree different Hfr donor strains are mixed with separate samples of an F− strain, and the following mapping data are provided from studies of interrupted conjugation: Appearance of genes in F − cells Hfr1: Genes b+ d+ c+ f+ g+ Time* 3 5 16 27 59 Hfr2: Genes e+ f+ c+ d+ b+ Time 6 24 35 46 48 Hfr3: Genes d+ c+ f+ e+ g+ Time 4 15 26 44 58 Construct a genetic map for these genes, indicating their order on the bacterial chromosome and the distances between them.arrow_forward
- 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 is the map distance (in minutes) between these two genes?arrow_forwardWhen the interrupted mating technique was used with five different strains of Hfr bacteria, the following orders of gene entry and recombination were observed. On the basis of these data, draw a map of the bacterial chromosome. Do the data support the concept of circularity?Hfr Strain 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_forwardDNA from a strain of Bacillus subtilis with genotype a* b* c* d* e* is used to transform a strain with genotype a b c d e. Pairs of genes are checked for cotransformation, and the following results are obtained: Pair of genes Cotransformation Pair of genes Cotransformatic a* and b* No b* and d* No a* and c* No b* and e* Yes a* and d* Yes c* and d* No a* and e* Yes c* and e* Yes b* and c* Yes d* and e* No On the basis of these results, what is the order of the genes on the bacterial chromosome?arrow_forward
- The figure below shows a partial chromosome map of an E. coli Hfr strain. Each mark = 10 minutes between conjugation transfer time. If transfer of genes begins at “*” relative to the origin of transfer, what is one of the predicted results from this map? It would take less than 30 minutes to transfer all of the genes that are shown. gal and azi will rarely be transferred together. gal and ton will rarely be transferred together. Ten minutes after transfer of ton, lac will be transferred. This strain will produce very few gal recombinants.arrow_forwardA bacterium of genotype a+ b+ c+ d+ is the donor in a cotransformation mapping. The recipient is a-b-c-d-. Data from the transformed cells is shown below. What is the order of the genes? a+ and b+ 5 a+ and c+ 2 a+ and d+ 0 b+ and c+ 0 b+ and d+ 0 c+ and d+ 5 cbad cadb bcda acbd bacdarrow_forwardYou discover a new bacteria and are interested in mapping its genome with respect to 10 genes. You are able to infer time-of-entry maps for four Hfr strains, which are pictured below. What is the map of the bacterial genome based on these Hfr experiments? Hfr1 Ga E Ne Hfr2 Sq Lix Tf Ne Hfr3 U I D Ga Hfr4 D U Sq O Sq - Lix - Tf - Ne -E- M- Ga - D -1-U O Sq - Tf - Lix -U -E-D- Ne -D -M- Ga OD-1-U- Sq - Lix - Ga - E -M- Tf - Ne OD- Ne - Ga -E- M - Sq - I-U- Tf - Lix O Lix - Ga - E - Sq -1-U- M -D- Tf - Nearrow_forward
- In 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_forwardIn the experiment of Figure shown, Lederberg and Tatum could notdiscern whether met+ bio+ genetic material was transferred to themet− bio− thr+ leu+ thi+ strain or if thr+ leu+ thi+ genetic materialwas transferred to the met+ bio+ thr− leu− thi− strain. Let’s supposethat one strain is streptomycin-resistant (say, met+ bio+ thr− leu−thi−) and the other strain is sensitive to streptomycin. Describe anexperiment that could determine whether the met+ bio+ geneticmaterial was transferred to the met − bio− thr+ leu+ thi+ strain orthe thr+ leu+ thi+ genetic material was transferred to the met+ bio+thr− leu− thi− strain. bio+ thr− leu− thi− strain.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.What information do you know based on the question and your understanding of the topic?arrow_forward
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