For High School Teachers
  From DNA to Organism: A Study in DNA Function for the High School Biology Classroom

Module 4: Yeast and the gene

Teacher suggestions for Module4:Qualitative analysis


            1 block for pre lab and setup
            10– 20 minutes 1– 3 days later for discussion

     What you need to set up

  • Yeast stock solutions (wild type, AKT-1 mutant)
  • 1 X 100ul pipette
  • 1 X 900ul pipette
  • Microcentrifuge tubes and racks
  • High K+ agar plates (1– 2 per group)
  • Low K+ agar plates (1– 2 per group)
  • Incubator at 37°C (for plates)
    • ~the plates can be grown at room temperature but it will take longer and increase the problem of contamination
  • Sterile water   
  • Optional:
    • Digital camera for data collection

     What the students need

  • 100ul of each yeast solution (wild type, AKT-1 mutant)
  • 4 X 2ml microcentrifuge tube
  • 1 X High K+ agar plate
  • 1 X Low K+ agar plate


     PreLab 10 minutes

           To prepare the students for this part of the lab module, they need to be familiar with the idea of a transgenic organism, specifically yeast. Introduce the idea that the gene they have been looking, from the plant, has been inserted into a yeast cell to attempt to determine what the gene will do. The yeasts have had their own potassium channels removed so that they will not interfere with our results. This is information that the students do not need but might help some of the more inquisitive ones to understand.

            The main goal of this activity is to familiarize students with one way to determine gene function but also to introduce them to methods for culturing microorganisms. It is a good idea to explain the idea of a serial dilution here and stress the importance of good lab protocol (including labeling your samples!)

     Lab 30-40 minutes

           The students should be fine to follow the protocol given for setting up the yeast cultures without too much help.

     PostLab 5 minutes clean up, 10-20 minutes discussion of results 1-3 day after

           Students can check their data after one day in the incubator but there is likely not to be too much going on. A 48-hour growth period for the yeast will yield better results.

           During the post lab, it is a good idea to put circles up on the board and use them to collect class data. I have found that there is always some confusion about which spots are whose and what the results mean. By collecting all of the data on the board, you can use overall data to draw conclusions and discuss problems that were had during the lab, (contamination, poor labeling, etc .). I generally have the students write up their lab reports based on the class data, not just their own.



           The lab write up is the homework that goes with this activity.