Practice Questions

TLS Online TPP Program

#Question id: 15618

Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1-, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac-). During an condition isolate a second Lac– mutation, which you designate lac2-. Using P1 phage on this strain and use the resulting phage lysate to infect the lac2- strain, selecting for Kanr transductants. In this case, all 100 Kanr transductants that are examined are Lac–. What does this result tell you about the relationship between the lac1- and lac2- mutations?

#Unit 13. Methods in Biology

lac1- and lac2- mutations are very far from each other, they are linked, and are mutations in two different genes.
lac1- and lac2- mutations are very far from each other, they are unlinked, and are mutations in same genes.
lac1- and lac2- mutations are linked, and are mutations in same genes.
lac1- and lac2- mutations are very far from each other, they are unlinked, and are mutations in two different genes.