Membrane Function Lab Planning – Hour 4, Group 4

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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7 Responses to Membrane Function Lab Planning – Hour 4, Group 4

  1. Nick S says:

    The independent Variable is the health of the cell if i’m correct, so we could run multiple experiments we could test the validity of the experiment.

  2. Mary W. says:

    I also think the independent invariable will be if the cell is alive. The dependent variable will then be weather or not the Congo red comes out of the cells. I also think the experiment should be us observing the cells before the dye, and then put dye in the dead and alive cells. The cells that are alive will probably be able to remove the dye, while the dead ones will probably remain red. In order to make sure we have good results we can do this mulitple times. I think this will work but i may be wrong.

  3. John C. says:

    The constant variables will be the type of dye we use (Congo Red), and the temperature that we boil the samples of yeast in. These are constant because we are not testing them. Making use of the unique properties of the yeast immune system will be quite easy in this lab, all we must observe is whether the Congo Red is removed or not, from both the living and (quite presumably) dead yeast cells. The living yeast cells should take out the Congo Red by the process of exocytosis, whereas the dead yeast cells will retain the Congo Red, as their immune system is redundant and will not function anymore. Redoing this test is a must so that we can prove our validity.

    See you tomorrow~

  4. Travis K. says:

    I agree with all of you, and as we need a control group, I think that should simply be dead yeast cells. This will ensure that it is, in fact, the fact that it is exocytosis that is causing the cells to expel their dye. Thank you all and I will see you tomorrow.

  5. Nick S says:

    Yes, I think a control group will be better than just repeating the trials

  6. Travis K and Nick S says:

    We found that our hypothesis that the stain moves into the yeast cells through passive transport and moves out of the yeast cells through active transport, is correct. The congo red was expelled by the alive yeast cells. We know this because we obeserve1d the cells and found that our hypothesis was correct and the alive cells changed from dark red to light red. There were some sources of error including the failed control group as well as inaccurate measures in our experiment.

  7. Mary W. and John C. says:

    The procedure for this is to first put a sample of Alive yeast cells onto a slide and observe them, and then do the same with dead(boiled)yeast cells. Then put a drop of Congo red on both slides and let the dye settle into the cells. Then, we must get a drop of water and put it on one side of the slide and then put a paper cloth on the other side of the slide. Next, we put the slide under the microscope, an focus on the correct cells. Observations should be written down and and analyzed. Do this with both the alive and dead cells.

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