Purpose:

The purpose of this experiment is to become better at using laboratory techniques such as calculating the concentration of cells by using serial dilutions.  We are also learning new techniques such as micropipetuting and how to complete serial dilutions.

Procedure:

1.  Add 90 ul of PPT in 4 test tubes.  Make sure you are using the right micropipette.
2. Take 10ul from the first test tube and add it into the second tube (10^-2).   Stir.
3. Repeat steps by adding 10ul of the second tube into the third then stir and 10ul of the third tube into the fourth then stir.
4. Place 5ul of all four dilutions (10^-1 to 10^-4) onto a clean concavity slide.
5. Count and record number of cells in each 5ul droplet.

Data and Observations:

• average cell counts/5ul
• Average cells per ul in the drop
• Average cells/ul in the undiluted sample
• Average cells/ml in the undiluted sample

10^0

• about 90/5ul
• 18/1ul/drop
• 1800/1ul/sample
• 1800000

10^-1

• 9/5ul
• 1.8/1ul/drop
• 180/1ul/sample
• 180,000/ml

10^-2

• 0/5ul
• 0/1ul/drop
• 0/1ul/sample
• 0/ml

10^-3

• 0/5ul
• 0/1ul/drop
• 0/1ul/sample
• 0/ml

10^-4

• 0/5ul
• 0/1ul/drop
• 0/1ul/sample
• 0/ml

Conclusion:

This experiment made me familiar with micropipetting and creating serial dilutions which will be necessary in future experiments.