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.
Want to see more full solutions like this?
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_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_forward
- In 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_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_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_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 information do you know based onthe question and your understanding of the topic?arrow_forward
- In 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_forwardWe have two specific strains of E. coli that have shown horizontal gene transfer (HGT) when mixed. To experimentally determine the method of HGT that is happening, the following conditions are set up in different tubes of culture media: A) Donor and recipient strain mixed together (control - no treatment). B) Donor and recipient strains mixed together, DNase added (can digest DNA in solution, not within cells).C) Special tube containing a membrane filter (with pores that allow DNA and viruses to pass through, but not bacterial cells) that separates two compartments. Donor strain is added on one side, the recipient strain on the other (they are separated by the filter).D) Donor and recipient strains mixed together, with chemical that inactivates viruses (chemical affects bacteriophages in solution so they are unable to attach to cells). The results: Tubes A, B, and D: HGT was observed. Tube C: HGT was NOT observed. Based on this, which type of HGT was occurring? Conjugation,…arrow_forwardIn the transformation experiment by Griffith, two strains of an organism was injected into a mouse model. One, he labelled S was a heat-killed but pathogenic strain while the other, R was a non- virulent or non-pathogenic strain. Within 48 hours, the mouse died and only the S strain was obtained from the dead mouse. What conclusions can you derived from this experiment? A. Some of the pathogenic S strains survived, proliferated and subsequently overpowered the R strain. B. The R strains mutated and were converted to a pathogenic S strain. C. The R strains assimilated the DNA from the S strain and were transformed into the S strain. D. The R strain DNA hybridized with the S strain DNA such that the daughter DNA of the new generation of R all contained the S DNA. E. All of these conclusions are possible.arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning