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Transformation Efficiency Calculations
transformation efficiency is the number of antibiotic-resistant colonies per mg
of plasmid DNA
10 mL of plasmid were used; the concentration of
the plasmid was 0.005 mg/mL
total mass = [10 mL][0.005 mg]
= 0.05 mg plasmids
[ 1 mL]
total volume = [10 mL plasmids]+[250 mL
CaCl] + [250 mL luria broth] = 510 mL
suspension
fraction spread on plate = volume suspension spread/total volume suspension
= [100 mL] = 0.196
[510 mL]
mass of plasmid in cell suspension spread = total mass plasmid x fraction
spread
= [0.05 mg] x [0.196] = 0.0098 mg
transformation efficiency = # colonies per mg
plasmid DNA / mass plasmid spread
transformation efficiency LB/Amp with Amp+/X-gal +
= 63 / 0.0098 = 6.4 x 103 colonies/mass plasmid spread
transformation efficiency LB/Amp/X-gal with Amp+/X-gal +
= 47 / 0.0098 = 4.8 x 103 colonies/mass plasmid spread
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