micro bio prelab 3.docx

# micro bio prelab 3.docx - Prelab Questions Question 1...

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Unformatted text preview: Prelab Questions Question 1: Formula for dilution is C1V1 = C2V2 C1 (concentration of initial solution) = 15% C2 (concentration of final solution) = 0.1% V1 (Volume of initial solution) = Not known V2 (Volume of final solution) = 50 ml Calculation: After putting all the values in above equation: 15% V1= 0.1% X 50 ml V1= (0.1 % X 50 ml)/15 % = 5/15 = 0.33 Therefore, 0.33 ml of 15% NaCl solution should be mixed to 46.67 ml of distilled water to make a final volume of 50 ml. Question 2: from 1ml of 2x108 cells/ml add in to 9 ml of water (now dilution is 10 times 2x107), from above solution take 1ml and add in to fresh 9ml water (now dilution is 100 times 2x106) from above solution take 1ml and add in to fresh 9ml water (now dilution is 1000 times 2x105). from above solution take 1ml and add in to fresh 199ml water (now dilution 2x105/200 or 2x105/2x102 = 1x103). we have 2*108 cells/ml now 100 times dilution (1 ml in 100 ml) give us 2*106 cells/ml. again 100 times dilution give us 2*104 cells/ml. now 10 times dilution give us 2*103 cells/ml. and half dilution (1ml + 1ml) will give us 1*103cells/ml. so overall dilution is 100*100*10*2 = 2*105 times dilution. Question 3: cfu/ml in stock = No. of colonies/ml * dilution / volume plated. = 52*105 / 0.1 = 5.2*107 cfu/ml. Question 4: cfu/ml in urine sample = No. of colonies/ml * dilution / volume plated. = 37* 107 / 0.1 = 3.7*109 cfu/ml. ...
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• Winter '13
• Distillation, Sodium chloride, distilled water, C1V1

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