Membrane Function Lab Planning – Hour 1, Group 2

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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6 Responses to Membrane Function Lab Planning – Hour 1, Group 2

  1. Lauren L says:

    Independent: the yeast
    Dependent: how the congo red passed through the membrane
    Constants: type/brand of yeast and congo red dye
    Evidence: If the size of the cell changes slightly then we know that the congo red dye has passed through. The congo red will also leave the yeast slightly tinted.
    Confidence if the validity: We will complete three trials.
    Control Group: We will do one of the trials without congo red.

    Procedure:
    1. Place a drop of active yeast on a cover slide without congo dye or boiling. Observe and record results.
    2. Put equal amounts of yeast solution in two tubes.
    3. Boil the yeast in one of the tubes.
    4. Put equal amounts of red congo dye in each tube.
    5. Place a drop of each of 2 different slides then observe and record results.

    Does this sound good?

  2. Eastin W says:

    Nailed it. Looks good to me.

  3. John Gardner says:

    I think that it looks good but a couple things, we are doing the experiment under a microscope i believe so we wouldn’t put it in a tube but put it on a slide and use the method that we used last time to get water into the coverslip and forcing the congo red out. One other thing is that another constant is the dead (boiled) yeast to make sure that the congo red doesn’t move out of the cell without active transport. Overall looks good to me.

  4. Eastin W and John G says:

    Procedure:
    1. Gather materials
    2. Put dead yeast on first slide and alive yeast on second slide
    3. Place congo red dye (one drop) on both slides and stir with toothpick
    4. Cover with cover slip and wait 1 to 2 minutes
    5. Extract extra congo red with water technique
    6. Put under microscope and observe
    7. Record data for each test

  5. Lauren L. says:

    Conclusion: Our prediction was correct; it was that if the dye moves into the cells through passive transport and out the cells through active transport then the living cells will be changed back to their clear form and the dead ones will stay red throughout the experiment. In our experiment the unboiled/ alive cells returned to their original color because active transport occurred. The boiled/dead cells stayed red the whole experiment. This proves active transport flushed the red dye out of the cytoplasm of the living cells. The possible errors could have been the difference in amount of dye or yeast solution on each slide.

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