Question

Strain ! Strain II Amper Pen = penicillinC = chromosome Kan = kanyomycin P = plasmid Amp - ampicillinr = resistance Tet tetracycline Strains I and II are plated on "confirmation" plates, Fill in the table with a + or - according to whether ye think the bacteria will grown on the plate (+) or not (-). Strain ! Strain II + T Fronte + Amp + Tet + Kan + Pen + Kan + Tet + Kan + Amp + Tet + Amp + Pen + Kan Tet + Pen - - + - - +10 Pen + Kan

Answer 1

	Strain I	Strain II
Agar	+	+
+ amp	+	-
+ Tet	-	+
+ Kan	+	-
+ Pen	-	+
+ Kan +Tet	-	-
+ Kan + Amp	+	-
+ Tet + Amp	-	-
+ Pen + Kan	-	-
+ Tet + Pen	-	+

Presence of an antibiotic in a medium leads to the damage and ultimate death of a bacterium. However if it has a resitant plasmid it can grow even in the presence of the antibiotic. For ex - In the presence of antibiotic ampicillin, Strain I could survive becuase it had a ampicillin resistance plasmid. But strain II couldn't survive because it had no ampicillin resistance plasmid. Similarly in cases of where two antibiotics are present, it needs to be seen if the bacteria has resistance to both the antibiotics present in media. If the bacterium doesn't have resistance to even any of the the antibiotics, then it may lead to its death. For ex - In the medium where both Ampicillin and tetracycline are present, neither of the strains survive because strain I doesn't have any resistance to Tetracycline and strain II doesn't carry any resistance to Ampicillin.