Problem:

Question 1: Why is it important that the donor cultures (ie. E. coli) are grown to exponential phase, but the recipient cells can be in stationary phase?

Question 2: What is the selection for transfer of the F-plasmid from the donor? What is the counter-selection against the growth of the donor cells?

Question 3: What is the role of the r-m+ mutation? If the recipient strain in this conjugation experiement was an r-m+ strain of E. coli instead of the r+m+ of E. coli, how would you predict that the different recipient would affect the results and why?

Donor: E. coli K-12 EM499 (F'Tn10dTet) grown in tetraclyclin

Recipients: E. coli K-12 EM4, Salmonella MST 100, Salmonella 101; all grown in streptomycin

Provide a brief explanation for your answer.