Acridine orange is a chemical that inhibits the replication ofF- factor DNA but does not affect the replication of chromosomalDNA, even if the chromosomal DNA contains an Hfr. Let’s supposethat you have an E. coli strain that is unable to metabolizelactose and has an F factor that carries a streptomycin-resistantgene. You also have an F− strain of E. coli that is sensitive to streptomycinand has the genes that allow the bacterium to metabolize lactose. This second strain can grow on a lactose-containing medium.How would you generate an Hfr strain that is resistant tostreptomycin and can metabolize lactose? (Hint: F factors occasionally integrate into the chromosome to become Hfr strains, and occasionally Hfr strains excise their DNA from the chromosome to become F+ strains that carry an F′ factor.)

Acridine orange is a chemical that inhibits the replication ofF- factor DNA but does not affect the replication of chromosomalDNA, even if the chromosomal DNA contains an Hfr. Let’s supposethat you have an E. coli strain that is unable to metabolizelactose and has an F factor that carries a streptomycin-resistantgene. You also have an F− strain of E. coli that is sensitive to streptomycinand has the genes that allow the bacterium to metabolize lactose. This second strain can grow on a lactose-containing medium.How would you generate an Hfr strain that is resistant tostreptomycin and can metabolize lactose? (Hint: F factors occasionally integrate into the chromosome to become Hfr strains, and occasionally Hfr strains excise their DNA from the chromosome to become F+ strains that carry an F′ factor.)

Biology Today and Tomorrow without Physiology (MindTap Course List)

5th Edition

ISBN:9781305117396

Author:Cecie Starr, Christine Evers, Lisa Starr

Publisher:Cecie Starr, Christine Evers, Lisa Starr

Chapter10: Biotechnology

Section: Chapter Questions

Problem 1CT

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