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
Biology
- By 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_forwardYour 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_forwardYou can carry out matings between an Hfr and F strain by mixing the two cell types in a small patch on a plate and then replica plating to selective medium. This methodology was used to screen hundreds of different cells for a recombination-deficient recA - mutant. Why is this an assay for RecA function? Would you be screening for a recA mutation in the F or Hfr strain using this protocol? Explain.arrow_forward
- Consider 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 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_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
- Four Hfr strains (A, B, C, D), were all derived from a F+ strain of E. coli. When each strain is used as a donor in an interrupted-conjugation experiment, the entry times of the first five markers are indicated in the table below (time of entry in minutes is indicated in brackets). Below is a partial map of the F+ strain (distances not proportional). Match the position of all genes with their correct position on this map. Strain A ala+ (5) ser+ (10) ade+ (15) his+ (25) val+ (30) 3 5 2 7 4 1 6 Strain B ade+ (12) his+ (22) val+ (27) pro+ (42) met+ (45) > sert ade+- 1. lac+ his+ ala+ met+ mal+ pro+ val+ Strain C pro+ (1) met+ (6) lac+ (11) mal+ (21) ala+ (31) 7. Strain D met+ (10) pro+ (15) val+ (30) his+ (35) ade+ (45) 2. 6. 3. 5. 4. 1. position #1 2. position #2 3. position #3 4. position #4 5. position #5 6. position #6 7. position #7arrow_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_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 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_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 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_forwardIn E. coli, the gene bioD+ encodes an enzyme involved in biotin synthesis, and galK+ encodes an enzyme involved in galactose utilization. An E. coli strain that contained wild-type versions of both genes was infected with P1 phage, and then a P1 lysate was obtained. This lysate was used totransduce (infect) a strain that was bioD− and galK−. The cellswere plated on a medium containing galactose as the sole carbonsource for growth to select for transduction of the galK+ gene.This medium also was supplemented with biotin. The resultingcolonies were then restreaked on a medium that lacked biotin tosee if the bioD+ gene had been cotransduced. The following resultswere obtained:What topic in genetics does this question address?arrow_forwardYou 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_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning