Membrane Function Lab Planning – Hour 4, Group 6

Consider the following questions to help you get started:

  • What variable will you be testing (independent variable)?
  • What variable(s) will you be measuring (dependent variable)?
  • What variables will you hold constant (constant variable)?
  • What evidence would confirm that the stain has crossed the membrane?
  • How will you be confident in the validity of your results?
  • What will you use as a standard of comparison (control group)?

Use the comment form below to discuss the plan for your experiment.

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5 Responses to Membrane Function Lab Planning – Hour 4, Group 6

  1. River P says:

    The best way to prove our hypothesis is basically what Mr. Mohn said in class. We need to dye a group of dead yeast cells red. When we look at them under the microscope, they should appear red. Then, we can look at live yeast cells dyed red under the microscope. If they are clear, then they would have had to push the dye out of their cytoplasm. This would prove our hypothesis correct.

    • Rafael B. says:

      Ok, so that is a good procedure and perhaps the independent variable is the yeast cells (boiled and unboiled)? The Congo red could be a constant and perhaps the dependent variables is whether or not the cells clears the Congo red out of its cytoplasm. We should test the procedure three times just to insure the validity of our results. And we could used the boiled yeast a control group to make sure that we know what would happen if we had dead yeast cells. And the way we would know it crossed the membrane is that we would see the dye go inside the cell and perhaps be expelled or not. Please correct me if any of you disagree with this.

      • Michael B. says:

        I disagree with Rafael, I think the independent variable is the amount of Congo Red used, because using an incredible amount will overwhelm the cell. I do agree that the dependent variable is the cell’s ability to clear the dye out of the cytoplasm.

  2. Rafael B. & Hayden F says:

    The procedure started with gathering the materials. First, you put the yeast cells on the slide and then apply the Congo red to the slide. Wait for 3 minutes and then clear the slide of Congo red. Put the slide under the microscope and then observe and record. Take the other slide and apply the dead (boiled) yeast cells. Then apply the Congo red and wait 3 minutes. Clear the Congo red and then put the slide under the microscope and then observe and record. Repeat this procedure once.

  3. Michael B. and River P. says:

    Our hypothesis, for the most part, was correct. The dead yeast cells in the first trial were a light orange color but this was because the dye hadn’t been on the cells long enough. The second trial had went exactly as predicted with the yeast cells being able to effectively pump the Congo Red out of it’s cytoplasm. There is one major possible error source and that is the amount of time the yeast cells were in contact with the red dye was not consistent throughout the experiment.

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