When Do Adaptive Mutants Arise in Yeast?

 

Michael D. Dennison and Corey A. Goldman

Tested Studies in Laboratory Teaching, 1994, Volume 15

Abstract

This exercise examines when adaptive mutations arise in a population. Students prepare cultures of baker’s yeast on normal agar media and then transfer the exact spatial pattern of these colonies to agar plates containing copper using the replica-plating technique. They compare the pattern of mutant colonies on the two replicate plates to test when copper-tolerant mutants arose. If the colony positions match then the mutants pre-existed in the original population (spontaneous mutation). If colonies do not match then this supports a hypothesis that mutants were induced by exposure to the copper. Students learn skills such as preparing agar plates, the sterile technique, replica-plating, and the use of pipets and dilutions.

Keywords:  mutation, yeast, replica plating, copper-tolerant mutants

University of Toronto (1993)