Concept explainers
An interrupted mating study is carried out on Hfr strains
a. For each Hfr strain, draw a time-of-entry profile like the one in Figure
b. Using the chromosome map you prepared in answer to Problem
c. Explain why azi is the last gene of strain
d. Write out the interrupted mating results you would expect after
e. In minutes, what is the total length of the chromosome in the donor species?
Want to see the full answer?
Check out a sample textbook solutionChapter 6 Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
- 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_forwardA yeast geneticist irradiates haploid cells of a strain thatis an adenine-requiring auxotrophic mutant, caused bymutation of the gene ade1. Millions of the irradiatedcells are plated on minimal medium, and a small number of cells divide and produce prototrophic colonies.These colonies are crossed individually with a wildtype strain. Two types of results are obtained:(1) prototroph × wild type : progeny all prototrophic(2) prototroph × wild type : progeny 75% prototrophic,25% adenine-requiring auxotrophsa. Explain the difference between these two types ofresults.b. Write the genotypes of the prototrophs in each case.c. What progeny phenotypes and ratios do you predictfrom crossing a prototroph of type 2 by the original ade1auxotroph?arrow_forwardAn Hfr strain that is hisE+ and pheA+ was mixed with a strain thatis hisE− and pheA−. The conjugation was interrupted and the percentageof recombinants for each gene was determined by streakingon a medium that lacked either histidine or phenylalanine. Thefollowing results were obtained:Determine the map distance (in minutes) between these twogenes.arrow_forward
- A series of Hfr strains that have genotype m+ n+ o+ p+ q+ r+ are mixed with an F− strain that has genotype m− n− o− p− q− r−. Conjugation is interrupted at regular intervals and the order of the appearance of genes from the Hfr strain is determined in the recipient cells. The order of gene transfer for each Hfr strain is What is the order of genes on the circular bacterial chromosome? For each Hfr strain, give the location of the F factor in the chromosome and its polarity. Hfr5 m+ q+ p+ n+ r+ o+ Hfr4 n+ r+ o+ m+ q+ p+ Hfr1 o+ m+ q+ p+ n+ r+ Hfr9 q+ m+ o+ r+ n+ p+arrow_forwardE. coli chromosomes in which every nitrogen atom is labeled (that is, every nitrogen atom is the heavy isotope 15N instead of the normal isotope 14N) are allowed to replicate in an environment in which all the nitrogen is 14N. Using a solid line to represent a heavy polynucleotide chain and a dashed line for a light chain, sketch each of the following descriptions:a. The heavy parental chromosome and the products of the first replication after transfer to a 14N medium, assuming that the chromosome is one DNA double helix and that replication is semiconservative.b. Repeat part a, but now assume that replication is conservative.c. If the daughter chromosomes from the first division in 14N are spun in a cesium chloride density gradient and a single band is obtained, which of the possibilities in parts a and b can be ruled out? Reconsider the Meselson and Stahl experiment: What does it prove?arrow_forwardConsider the following types of cells: F+, F-, Hfr, and F’ cells. Which of these four types of cells are capable of acting as a donor during conjugation? What genes does each cell that is capable of acting as a donor donate to the recipient cell?arrow_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_forwardThe presence (+) or absence (−) of six sequences in each of five bacterial artificial chromosome (BAC) clones (A–E) is indicated in the following table. Using these markers, put the BAC clones in their correct order and indicate the locations of the numbered sequences within them. Sequences BAC clone 1 2 3 4 5 6 A + − − − + − B − − − + − + C − + + − − − D − − + − + − E + − − + − −arrow_forwardPlease find the attachmentarrow_forward
- The following recombinants are recovered when conjugation occurs between an a*d*g+ donor and an adg recipient. at d+ g+ = 84% a d g+ = 6% at d g+ = 10% a dt g+ = less than 1% What is the map distance between the a and d genes? 10 map units 74 map units less than 1 map unit 84 map units 6 map unitsarrow_forward) In a conjugation experiment, we used two strains: Hfr: streptomycin sensitive and F-: auxotrophic for isoleucine and threonine, streptomycin resistant. If we interrupt conjugation when only threonine gene has been transferred and spread this mixture on: Minimal media, Minimal media with streptomycin Minimal media with threonine and streptomycin Minimal media with isoleucine and streptomycin LB agar plates with streptomycin On which plates do we expect bacterial growth? Why?arrow_forwardBACTERIA STRAIN A IS AUXOTROPHIC FOR METHIONINE AND STRAIN B IS AUXOTROPHIC FOR LEUCINE. A. WILL THESE STRAIN GROW ON MINIMAL MEDIUM (A MEDIUM THAT DOES NOT CONTAIN EITHER METHIONINE OR LEUCINE)? B. WHAT TYPE OF GENETIC RECOMBINATION MUST OCCUR TO RECOVER A PROTOTROPH?arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education