You can make up numerous dilution problems as a homework assignment. Some alternatives to seed beads include white and brown rice, larger beads, or glow-in-the-dark beads. You can experiment with alternatives to seed beads, but I found that the seed beads gave the best visualization results. Calculate the number of virus particles in your original sample using the following equation: number of beads/mL plated ×× 1/dilution factor = # virus particles/mL. Remember, the best plate to use is one that contains between 30 and 300 virus particles (green beads).ġ0. Use the tweezers to remove the green beads and place them into your beaker as you count them. Count the number of virus particles (green beads) in each dish and record your data in Table 1. Take 1 mL from each dilution tube and place it into the corresponding petri dish.ĩ. Shake the test tube well to mix the beads.ħ. Remove 1 m L of sample from the 10 −−4 test tube and place it in the 10 −−5 test tube. Shake the test tube well to mix the beads.Ħ. Remove 1 mL of sample from the 10 −−3 test tube and place it in the 10 −−4 test tube. Shake the test tube well to mix the beads.ĥ. Remove 1 mL of sample from the 10 −−2 test tube and place it in the 10 −−3 test tube. Notice that there are fewer green beads in the test tube.Ĥ. Shake the test tube well to mix the beads. Remove 1 mL of sample from the 10 −−1 test tube and place it in the 10 −−2 test tube.
Be sure to mix your beads until they are evenly distributed.ģ. Notice the distribution of green beads mixed in with the white beads. For this exercise, 1 mL will be represented by covering the bottom of the plastic beaker with the seed beads. Remove 1 mL of virus (green seed beads) from the original sample using the plastic beaker and place it in the 10 −−1test tube. For this exercise, 9 mL will be represented by filling the plastic beaker to just below the 10-mL mark. Obtain five test tubes and fill each with 9 mL of white seed beads (diluent) using the plastic beaker.