You may be able to completely skip this procedure if you have a supply of asci from some previous work. (See The Yeast Life Cycle for more information on mating and sporulating yeast)
1. Subculture the parent strains, HA1 and HB2, overnight on a YED plate.
2. Use sterile toothpicks to transfer a small amount of each parent strain to separate spots close to each other on the plate. Stir the parent strains together using a third sterile toothpick and then incubate the plate overnight.
3. Presporulate the diploids by transferring a small amount of the diploid culture to a fresh YED plate. Incubate the plate overnight.
4. To sporulate the diploid cells transfer several streaks of cells from the presporulation plate to a YEKAC plate. Incubate the plate for 3-5 days.
Rather than having the whole class make the cross (HA1 X HB2) suggested for this experiment you may wish to have several students perform the Getting Ready steps as a class demonstration. This will offer the opportunity for the whole class to review the steps of the yeast sexual life cycle. One plate of asci will supply enough ascospores for the entire class to do this spore analysis experiment.
Click here to return
Last updated Friday July 11 1997 :