Membrane Function Lab Planning – Hour 1, Group 3

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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16 Responses to Membrane Function Lab Planning – Hour 1, Group 3

  1. Emily says:

    Hi group 3! What ideas do we have for a procedure to follow? I believe that our procedure should have do so somewhat to the comparison of the live yeast to the dead yeast. So we need to figure out a way to encorporate that idea into one experiment. Just post your thoughts!

  2. Emily says:

    So we will be keeping the dye the same, and changing the type of yeast cell. Using the same dye, we will be able to compare how the dye affects the live yeast cell and the dead yeast cell.

  3. Morgan B says:

    Yeah I think that’s a great idea. This is what I think our procedure should be and we can write in our in steps later. But I think we should get all our materials and then we should do 2 experiments. One I think we should do it with the living yeast cells and see if the red dye will only dye the outside and keep the inside white. And our other experiment we should see if the dead yeast cells will do the same thing. If they do the same thing then it doesn’t require energy to send the dye out of the cell. But if it dyes the whole cell then it requires energy to send the dye out of the cell.

  4. Morgan B says:

    I’m not quite sure on the variables but here what I think and correct me if I’m wrong.
    The independent variable is yeast cells.
    The dependent variable is the color of the yeast cells-I’m not quite sure if that’s right but that’s what I’m thinking.
    The constant variable is the color and type of the dye .
    I think the control group is the color and type of the dye as well.

    • Morgan B says:

      or the control group could be type of yeast we are using.

      if you guys have any input that would be great.

    • Shaurir R says:

      I think the control is the type of cell (dead or alive)
      the dependent is right
      the independent is right
      the constant is right, you might include towels, water, slides, and other lab materials

  5. Morgan B says:

    I kinda said this a little bit, but we know that the dye has crossed the membrane and stained it if the whole yeast cell is dyed. If only the outside of the cell wall of the plasma membrane is stained then the plasma membrane is constantly pumping the dye back out of the cell.

  6. Shaurir R says:

    Also, we can contrast with the dead yet cell because that one will not release the dye because it is dead. That might be a control.

  7. Shaurir R says:

    We have found the control and the variables so I will do the remainder

  8. Shaurir R says:

    The evidence that the stain crossed the membrane would be that the yeast cell turns red, and if the dye crosses the membrane out, the yeast cell is white.

    In order to test the validity of our results, some possibilities may be that we can repeat the experiments if we have time, or we could compare the results and make the strongest inference or conclusion matching our results based off of our previous information on the types of transport.

  9. Shaurir R says:

    I think that concludes our discussion. Feel free to leave any comments when you read this and I could get back to them.


  10. Emily says:

    Thank your Shaurir and Morgan! I think that we have a clear image for what to do in our experiment tomorrow. I can’t wait to observe what happens tomorrow!

  11. Shaurir R says:

    Morgan will not be here today.

  12. Emily F. says:

    Our procedure is as follows, First, retrieve both types of yeast cells. Second, place the two types of cells on two different slides. Third, place congo red on and mix together with the yeast cells. Fourth, apply cover slips to the slides with the cells and congo red. Fifth, apply paper towel and draw out excess dye and water. Next, observe under multiple powers of the microscope. Then, record observations, and if time allows redo all of the experiment again. Finally, clean supplies and draw conclusions.

  13. Shaurir R says:


    Based off of our results, we have come to the conclusion that if the stain moves into the yeast cells through passive transport and out of the cell through active transport, then we know the yeast cell is alive. This means our hypothesis was correct. Our evidence proves statement correct because the percentages of no red in the cell to all cells for the dead cells were miniscule compared to alive slides, which had a whopping 97.35% of cells excluding the dye from the cells. This means our hypothesis was correct and we had proper supporting data and evidence. However, some possibilities for human error include the amount of dye applied, how properly we stirred it, and whether we repeated the same conditions for each trial. All in all, we learned the processes of active and passive transport, and how cells can exclude certain materials using active transport.

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