6) You have an original concentration of 1.2 x 10^7 org/mL...

6) You have an original concentration of 1.2 x 10^7 org/mL and you want to obtain a final concentration of 3 x 10^2 org/mL. a. Draw a dilution scheme with the following information on your diagram: i) the sample volume transferred and the volume of the diluent at each step RESTRICTION: Final volume for each tube can be no more than 5 mL and no less than 2 mL. ii) the dilution at each step iii) the dilution factor at each step iv) the total dilution factor at each step v) the concentration at each step b. Then, calculate how many CFUs you would expect to see if you plated a total volume of 200 uL of the last dilution tube.

Transcript

00:02 You have a cell stock with the original concentration of 1 .2 times 10 to the 7th power orc per mil.

00:08 And you want to obtain a final concentration of 3 times 10 to the second power orr per mil.

00:13 So first of all, you want to draw a dilution scheme with the following information.

00:19 So you want to indicate the volume that you transfer from a previous tube and the volume of diluent at each step.

00:25 So remember, your final volume cannot be no, can not be more than 5 mil and less than 2 mil.

00:32 You want to show the dilution at each step, dilution factor at each step, total dilution factor at each step, and the concentration at each set.

00:41 So first of all, we want to calculate a total dilution.

00:44 This can be done by the original concentration divided by the final concentration.

00:48 So we can plug in the number that we have from the question.

00:51 The original concentration is 1 .2 times 10 to the 7th c .fu per mill.

00:57 And the final concentration is three times 10 to the second power cfu per mill.

01:01 So after the calculation, our total dilution is four times centered fourth.

01:08 This equals 40 ,000.

01:10 So we want to dilute our original concentration or tube to 40 ,000 times.

01:18 So underneath the calculation, i'm drawing this scheme right here.

01:22 So the first tube we call the original tube.

01:25 So i plan to take 20 -maclitre out from the original stock and then add into new youtube with 1980 microliter of medium.

01:36 So 20 plus 1980 equals 2 ,000.

01:41 So you go from 20 mic liter to 2 ,000 mic liter, which is 2 militer.

01:48 So it's a 1 to 100 dilution.

01:50 So for this step, it's a 1 to 100 dilution.

01:53 The total dilution is also 1 to 100.

01:56 Since our original concentration is 1 .2 times times 10 to the 7th power after 1 to 100 dilution, the concentration in this tube is 1 .2 times 10 to the fifth power.

02:13 So this is the step number one.

02:16 The second step, i will repeat this step.

02:19 So i take another new tube, and then i take 20 microliter out from the tube number one, and then i add 1980 micliter of medium again...

Question

Please give Ace some feedback