A group of genetics students mix two auxotrophic strains of bacteria: one is leu+ trp+ his− met− and the other is leu− trp− his+ met+. After mixing the two strains, they plate the bacteria on minimal medium and observe a few prototrophic colonies (leu+ trp+ his+ met+). They assume that some gene transfer has taken place between the two strains. How can they determine whether the transfer of genes is due to conjugation, transduction, or transformation?

A group of genetics students mix two auxotrophic strains of bacteria: one is leu+ trp+ his− met− and the other is leu− trp− his+ met+. After mixing the two strains, they plate the bacteria on minimal medium and observe a few prototrophic colonies (leu+ trp+ his+ met+). They assume that some gene transfer has taken place between the two strains. How can they determine whether the transfer of genes is due to conjugation, transduction, or transformation?

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter15: From Dna To Protein

Section15.1: The Connection Between Dna, Rna, And Protein

Problem 1SB

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You mix two auxotrophic strains of bacteria; one is leu+ trp+ his– met– and the other is leu– trp– his+ met+. After mixing the two strains, you plate the bacteria on minimal medium and observe a few prototrophic colonies (leu+ trp+ his+ met+). To determine whether gene transfer has occurred through conjugation, transformation, or transduction, you design an experiment in which you place filters between the two strains to see if gene transfer occurs. You set up three treatments:-Treatment A No filter, allowing contact between the bacterial strains-Treatment B Filter that blocks cells, but allows viruses and DNA through the filter-Treatment C Filter that blocks cells and viruses, but allows DNA through the filter When you check the results of your experiment, you find prototrophic colonies have occurred following treatments A and B, but not following treatment C. You conclude that gene transfer occurred through... Answer Choices Available: A) Conjugation B) Transformation C)…
You co-culture the following bacterial strains: an Hfr prototroph and an F- auxotroph for the genes mal, met, mtl, and xyl. You interrupt conjugation at various time points and place the mixtures on media plates lacking each of the nutrients. Based on the results shown on the right, what is the order of these four genes along the bacterial chromosome? Explain your reasoning.
You co-culture the following bacterial strains: an Hfr prototroph and an F- auxotroph for the genes mal, met, mtl, and xyl. You interrupt conjugation at various time points and place the mixtures on media plates lacking each of the nutrients. Based on the results shown in the image, what is the order of these four genes along the bacterial chromosome? Please explain!
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.
As mentioned in question 2 of More Genetic TIPS, origins oftransfer can be located in many different places on a bacterial chromosome,and their direction of transfer can be clockwise or counterclockwise.Let’s suppose a researcher conjugated six differentHfr strains that were thr + leu + tons str r azis lac + gal + pro + met +to an F − strain that was thr − leu − tonr str s azir lac − gal − pro −met −, and obtained the following results: Draw a map of the circular E. coli chromosome that shows thelocations and orientations of the origins of transfer in these six Hfrstrains.
You are studying a microorganism that contains a chloramphenicol acetyltransferase (CAT) enzyme, and looking for a clone of this microorganism that no longer contains the gene encoding CAT. Imagine you had an LB plate containing chloramphenicol. You streak an isolated colony of the Parent Strain and Clone A onto the same plate. Which of the following statements are true about the growth pattern after 24 hours in the incubator? Select all that apply? L-hlareeheticol LB chloremphenicel Parent Clune A Parent Clone A LD chlerephenicol 18 chloremphenitol Paremt Clone A Paront Clone A Plate A is the expected growth pattern as clone A should grow in the LB plate with chloramphenicol Plate B is the expected growth pattern as LB plate with chloramphenicol parent strain should grow in the Plate B is the expected growth pattern as clone A should not grow in the LB plate with chloramphenicol Plate A is the expected growth pattern as the parent strain should not grow in the LB plate with…
In your laboratory, you have an F − strain of E. coli that is resistant to streptomycin and is unable to metabolize lactose, but it can metabolize glucose. Therefore, this strain can grow on media that contain glucose and streptomycin, but it cannot grow on media containing only lactose. A researcher has sent you two E. coli strains in two separate tubes. One strain, let’s call it strain A, has an F factor that carries the genes that are required for lactose metabolism. On its chromosome, it also has the genes that are required for glucose metabolism. However, it is sensitive to streptomycin. This strain can grow on media containing lactose or glucose, but it cannot grow if streptomycin is added to the media. The second strain, let’s call it strain B, is an F − strain. On its chromosome, it has thegenes that are required for lactose and glucose metabolism. StrainB is also sensitive to streptomycin. Unfortunately, when strains A and B were sent to you, the labels had fallen off the…
Two auxotrophic triple Escherichia coli strains (A: met- phe- ade- val+ bio+ thr+ and B: met+ phe+ ade+ val- bio- thr-) are mixed in LB liquid medium, diluted and then spread on LB solid rich medium. Six colonies are observed: Then, replicates are performed on 6 different media (minimum medium + glucose + indicated substances). The results are shown below. Determine the genotype of the 6 colonies observed. Which ones are from strain A? From strain B? Which hypotheses can explain these results and which one do you prefer? met phe val bio Abbreviations: met ade val thr phe ade bio thr Met: methionine; Phe: phenylalanine; Ade: adenine; Val: valine; Bio: biotin; Thr: threonine.
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 information do you know based on the question and your understanding of the topic?
Using bacteriophage P22, you performed a threefactor cross in Salmonella typhimurium. The crosswas between an Arg− Leu− His− recipient bacteriumand bacteriophage P22, which was grown on an Arg+Leu+ and His+ strain. You selected for 1000 Arg+transductants and tested them on several selective media by replica plating. You obtained the followingresults:Arg+ Leu− His− 585Arg+ Leu− His+ 300Arg+ Leu+ His+ 114Arg+ Leu+ His− 1a. What are the cotransduction frequencies of argwith either his or leu?b. Is arg closer to his than it is to leu, or is arg closerto leu than it is to his? What are the relative mapdistances?c. Why can you not obtain an accurate cotransductionfrequency for his and leu from the data provided?d. What is the order of the three markers?e. Draw the crossovers that would produce the classwith only one transductant.f. Estimate the proportion of the 4.9 Mb S. typhimuriumgenome that contains these three genes. Assume thatbacteriophage P22 can package the same amountof DNA as the…
Linkage maps in an Hfr bacterial strain are calculated in units of minutes (the number of minutes between genes indicates the length of time that it takes for the second gene to follow the first in conjugation). In making such maps, microbial geneticists assume that the bacterial chromosome is transferred from Hfr to F − at a constant rate. Thus, two genes separated by 10 minutes near the origin end are assumed to be the same physical distance apart as two genes separated by 10 minutes near the F −attachment end. Suggest a critical experiment to test the validity of this assumption.
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 werethr+ leu+ tons strr azis lac+ gal+ pro+ met+ to an F− strain that wasthr− leu− tonr strs azir lac− gal− pro− met−, and obtained the followingresults:Draw a circular map of the E. coli chromosome that shows thelocations and orientations of the origins of transfer in these sixHfr strains.