Question

Assume the two E.coli shown below are allowed to conjugate

Strain 1: F+, Lac Z, histodine, leucine, ampicillin-resistant

Strain 2: F-, Lac Z, histodine -, leucine -, ampicillin-sensitive

What is the outcome of conjugation?

A) Strain 1 will become F- , LacZ-, histodine-, leucine-, and ampicillin-sensitive; Strain 2 will have an F+, LacZ, histodine+, leucine+, ampicillin-resistant genome

B) Strain 1 will remain the same, Strain 2 will have an F+, LacZ, histodine+, leucine+, ampicillin-sensitive genome

C) Strain 1 will remain the same, Strain 2 will have an F+, LacZ, histodine+, leucine+, ampicillin-resistant genome

D) Nothing will change because the two strains cannot conjugate.

Answer 1

Strain 1: F+, Lac Z, histidine, leucine, ampicillin-resistant

Strain 2: F-, Lac Z, histidine -, leucine -, ampicillin-sensitive

the F plasmid from the F+ strain moves to the strain 2 via sex pilus, so that genes in F plasmid is transferred to strain 2, since the strain 2 gets F plasmid it becomes F+.

F plasmid moves to the strain 2 via rolling circle replication, so the F+ strain remains as F+ even after conjugation,

strain 2 gets histidine +, leucine, ampicillin-resistant and LacZ genes from the strain 1.

so the answer is

C) Strain 1 will remain the same, Strain 2 will have an F+, LacZ, histodine+, leucine+, ampicillin-resistant genome