Membrane Function Lab Planning – Hour 4, 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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9 Responses to Membrane Function Lab Planning – Hour 4, Group 2

  1. AndrewH. says:

    OK so here is what I have so far:

    Independent Variable: Whether or not the yeast uses active transport to remove the Congo red from itself. (If You guys have a different variable I’m open to suggestions.)

    Dependent Variable: The amount of Congo red remaining in the yeast cells.

    Constant(s): 1) The amount of yeast solution. 2)The amount of Congo red solution.

    Control: So as to prove that our results aren’t a fluke, I recommend that we perform the same procedure we use on live yeast cells which will be listed below on dead yeast cells, just so we know what they would look like without active transport going on. Then I believe we should do this entire procedure twice.

    Procedure: 1)Obtain two slides, one containing live yeast cells, and one containing dead yest cells.
    2) Add the same amount of Congo red solution to both slides and use that paper towel and water method to remove the excess Congo red.
    3) Examine both slides immediately after step 2 and record observations.
    4) Wait about 5 minutes after step 3 and then examine both slides again.(This way there is time for diffusion and active transport to occur.)Record observations.
    5) Do steps 1-4 all over again.
    6) Analyze collected data and come to a conclusion of the hypothesis.

    • Rose YeganehKazemi says:

      I also got what you have for the independent variable, dependent variable, etc.
      Our independent variable is if the yeast cells use active transport to remove the Congo red dye. Our dependent variable is the amount of Congo red dye still remaining in the yeast cells and our constants are the amount of yeast solution and the amount if the dye initially put with the yeast cell. For our control, we will perform the procedure with live yeast cells and then another time with the “dead” yeast cells. Our materials are a microscope, a slide and slide cover, the Congo red dye, safety googles, a paper towel, living yeast cells and “dead” yeast cells.
      #1) Get two slides with one having the living yeast cells and the other having the dead yeast
      #2) Add equal amounts of the Congo red dye to both of the slides and use a paper towel and use the method to remove the excess Congo red that we used with the cheek cells with the blue dye.
      #3) Look at both slides under the microscope and record what you see
      #4) Wait a few minutes and look at the slides again. Record what you see too.
      #5) Re-do steps #s 1-4 all over again.
      #6) Examine the data and write a conclusion

      • Jaelen M says:

        Yeah, I agree. I got the same for the independent variable being the yeast cells using active transport to get rid of the dye. The dependent variable being the amount of dye remaining in the cell. The constants being the amount of dye put into each cell and the amount of yeast solution. Our control is that we will perform this on both dead and alive cells and perform the procedure twice. I agree completely with the procedure you guys have posted.

      • Caden H says:

        I think that the procedure you thought of is exactly what we are supposed to do. We will be able to get different results from the live and dead yeast cells, and we can use the dead yeast cells as a control. Repeatig the process as well will give us more accurate results, and the entire procedure sounds great.

  2. AndrewH. says:

    If you guys have any concerns or want to change anything in the procedure please feel free to edit it.

  3. AndrewH. says:

    Also, if you guys would like, I can make tables and areas to draw diagrams to help keep track of observations so it looks nice and uniform instead of trying to cram it all into the space we’re given. I did it for the last lab.

  4. Caden H and Andrew H says:

    We got two slides, one with live and healthy yeast cells and one with dead yeast cells. We put each one of them under a microscope, and examined the visual properties that we noticed. We recorded our results on the sheet that Andrew created. We then added a drop of Congo red to each slide and IMMEDIATELY examined the cells. We took note of how many cells were red, and made an estimate ratio of red cells:green cells, and then turned it into a percentage and recorded the results. We then gave the slides 5 minutes to set, so diffusion was able to occur. After the 5 minutes were up, we examined each slide again and then made the estimate ratio and percentage and recorded the results as we did before.

  5. Rose YK and Jalen M says:

    Based on our findings, we proved our hypothesis correct. The yeast cells used active transport to remove the dye and used passive transport to get the dye into the yeast cells. The healthy yeast cells used active and passive transport. Sources of error include inaccurate measurements of the dye and an unequal amount of yeast on the slides.

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