Concept explainers
To determine: Which type of nutrient medium would a double mutant with argG and argE grow on.
Introduction: Beadle and Tatum selected Neurospora crassa, the bread mold for their experiments. They allowed the growth of cultures in a nutrient-rich medium and then subcultured individual fungal cells by placing them on minimal medium. This process enables the identification of cells that lost the capability to synthesize compounds essential for growth. They aimed to study the capability to synthesize arginine amino acid.
Explanation of Solution
Beadle and Tatum selected mutants that can survive and grow on minimal medium with arginine. This resulted in a set of independent mutants that cannot synthesize arginine, and each of these mutants could be mapped genetically to different chromosomal positions. This research described four genes, namely argE, argF, argG, and argH. The specific lesion in each mutant can be determined by adding specific intermediates in the arginine biosynthesis pathway. Growth should be observed if the mutation influences the enzyme that occurs earlier in the biochemical pathway than the intermediate added to the minimal medium. No growth should be observed if the mutation influences an enzymatic step that occurs after the intermediate added.
The ArgE mutants are obstructed at the first step in the pathway. Therefore, the double mutant strain with argG and argE would grow only on nutrient medium supplemented with all the reaction intermediates.
To describe: What can a double mutant say about the order of the genes.
Explanation of Solution
Generally, these types of double mutants enable researchers to conclude which gene exists first in the pathway. The double mutant will appear like an organism with a mutation at the initial point in the biological pathway.
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Chapter 15 Solutions
1 SEM ACC W/RAVEN CARDED
- From an Escherichia coli strain, five Hfr strains were isolated. The location and orientation of the transfer origin of each Hfr strain is shown in Figure 1. You want to use these five strains to map the locus responsible for thiamine synthesis, called thi. Each Hfr strain is sensitive to rifampicin (Rifs) and thi*. Conjugation experiments are performed between each of the Hfr strains and an F strain Rif Thi™. 0 T leu 10 20 T nadD pyrC trp 40 T his 60 70 2) The results are shown in the following table: Donor strain Hfr1 Hfr2 Hfr3 Hfr4 Hfr5 cysG 80 90 1) What is the selection medium used in these conjugation experiments metA Colonies Thi+ 1000 0 400 0 25 100 Hfr1 Hfr2 Figure 1: Chromosome map of Escherichia coli. Five Hfr strains (Hfr1 to Hfr5) were isolated and the location and orientation of the origin of transfer is shown by the arrows in each Hfr strain. Distances in minutes are shown. Leu: leucine biosynthesis; nadD: NAD biosynthesis; pyrC: pyrimidine biosynthesis; trp: tryptophan…arrow_forwardBy conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample of theirexperimental results is shown in the following table:Analyze data. Compare and contrast. Make a drawing.arrow_forwardIn a cotransformation experiment (see question 4 of More GeneticTIPS), DNA was isolated from a donor strain that was proA+ andstrC+ and sensitive to tetracycline. (The proA and strC genes conferthe ability to synthesize proline and confer streptomycin resistance,respectively.) A recipient strain is proA− and strC− and isresistant to tetracycline. After transformation, the bacteria werefirst streaked on a medium containing proline, streptomycin, andtetracycline. Colonies were then restreaked on a medium containingstreptomycin and tetracycline. (Note: Each type of medium hadcarbon and nitrogen sources for growth.) The following resultswere obtained:70 colonies grew on the medium containing proline, streptomycin,and tetracycline, but only 2 of these 70 colonies grew whenrestreaked on the medium containing streptomycin and tetracyclinebut lacking proline. If we assume the average size of the DNA fragments is 2 minutes,how far apart are these two genes?arrow_forward
- Your TA gives you an Escherichia coli strain (AmreB) that carries a gene deletion in the mreB gene. As a result, the strain is not able to produce the MreB protein. Your task is to compare the morphology of actively growing AmreB cells to the parental wildtype strain (produces MreB). What difference in morphology will you likely observe? Would you expect the same in Staphylococcus aureus?arrow_forwardConsider the following experiment. First, large populations of two mutant strains of Escherichia coli are mixed, each requiring a different, single amino acid. After plating them onto a minimal medium, 45 colonies grew. Which of the following may explain this result? A) The colonies may be due to back mutation (reversion). B) The colonies may be due to recombination. C) Either A or B is possible. D) Neither A nor B is possible.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_forward
- You have isolated 8 mutants in yeast that fail to grow on minimal media plates but do grow when they are supplemented with Arginine. You know that Arginine is synthesized in a biochemical pathway within wild-type yeast, but you do not know how many gene products it takes for the pathway. You have all of the lines as both a and a cells and mate each strain to each other in pairwise crosses and plate them on minimal media to see if they grow. You obtain the following results with (+) representing growth, and (-) indicating no growth: a 1 5 1 a 4 5 6 7 8 How many genes are represented? O 1 3 7 O Cannot tell from the data a + + + + + • + + i 0 +, + + + • + + 7 + + + + + , . + + + + + m + + + + + + + 2 + + + + + i + -I + + . . + + +arrow_forwardIn this problem, just put the order of the intermediates on the pathway, starting with P and ending with Z and explain your reasoning. (So to get you started, notice the class 1 mutants—and there is only mutant in this class, which is mutant #5—won’t grow on minimal medium, but will grow if you give it substance Z. However, giving it substances, p, w, x, or y won’t help. This means that the gene that is mutated lies on the pathway in a place that the Z substances is to its right and all the other substances are to its left. The easiest next one to look at is the line with 2 pluses, and then the line with 3 pluses, and then the line with 4 pluses).arrow_forwardBy conducting conjugation experiments between Hfr and recipientstrains, Wollman and Jacob mapped the order of many bacterialgenes. Throughout the course of their studies, they identified severaldifferent Hfr strains in which the F-factor DNA had been integratedat different places along the bacterial chromosome. A sample of theirexperimental results is shown in the following table:What information do you know based on the question and your understanding of the topic?arrow_forward
- From one Escherichia coli strain, five Hfr strains were isolated. The location and orientation of the origin of transfer of each Hfr strain are shown in Figure 1. want to use these five strains to map the locus responsible for thiamine synthesis, called thi. Each Hfr strain is sensitive to rifampicin (RifS) and Thi+. Conjugation experiments are performed between each of the Hfr strains and an F- RifR Thi 9 leu 10 20 30 nadD pyrC trp 40 his 50 60 70 cysG 80 90 metA 100 Hfr1 Hfr2 Hfr3 Hfr4 Hfr5 Figure 1: Chromosome map of Escherichia coli. Five Hfr strains (Hfr1 to Hfr5) were isolated and the location and orientation of the origin of transfer is shown by the arrows in each Hfr strain. Distances in minutes are indicated. Leu: leucine biosynthesis; nadD: NAD biosynthesis; pyrC: pyrimidine biosynthesis; trp: tryptophan biosynthesis; his: histidine biosynthesis; cysG: cysteine biosynthesis; metA: biosynthesis of methionine. 1) What is the selection medium used in these conjugation…arrow_forwardFrom one Escherichia coli strain, five Hfr strains were isolated. The location and orientation of the origin of transfer of each Hfr strain are shown in Figure 1. want to use these five strains to map the locus responsible for thiamine synthesis, called thi. Each Hfr strain is sensitive to rifampicin (RifS) and Thi+. Conjugation experiments are performed between each of the Hfr strains and an F- RifR Thi leu 10 20 T nadD pyrC trp 30 his Donor strain Hfr1 Hfr2 Hfr3 Hfr4 Hfr5 The results are shown in the following table 60 70 cysG Colonies Thi 1000 0 400 0 25 80 90 metA 1,00 Hfr1 Hfr2 Figure 1: Chromosome map of Escherichia coli. Five Hfr strains (Hfr1 to Hfr5) were isolated and the location and orientation of the origin of transfer is shown by the arrows in each Hfr strain. Distances in minutes are indicated. Hfr 3 Leu: leucine biosynthesis; nadD: NAD biosynthesis; pyrC: pyrimidine biosynthesis; trp: tryptophan biosynthesis; his: histidine biosynthesis; cysG: cysteine biosynthesis; metA…arrow_forwardFour Hfr strains are derived from an F+ strain of E. Coli to serve as donors for an interrupted-mating experiment. Use the time-table and partial map of the F+ strain (shown below) to determine the genes’ respective positions. Keep in mind that the map distances are NOT proportional, only the FIRST 5 markers are indicated per strain, and the entry times, recorded in minutes, are in parentheses. Transferred genes represent wild-type alleles. Based on the data, which gene can be located at position 5 on the map?arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning