Manipulation of yeast respiration using acetic acid to demonstrate the Scientific Method

 

Tested Studies in Laboratory Teaching, 2010, Volume 31

Keller, M. J. & C. Gilliam

Abstract

The application of the Scientific Method to realistic scenarios using authentic experiments should be an important component of the teaching laboratory. As part of a large introductory biology lab course, the manipulation of yeast respiration has proven to be a reliable, engaging exercise showcasing hypothesis generation and testing. Recent research on Saccharomyces cerevisiae cells has demonstrated that at low pH acetic acid interferes with glucose metabolism and can induce apoptosis. In the teaching lab, we have implemented protocols for testing hypotheses addressing the possible effects of acetic acid on CO₂ production by yeast as measured by a simple respirometer, including (1) suppression of glucose metabolism, (2) reduced cell proliferation, and (3) enhanced cell death. Students generate hypotheses based on a fictitious scenario, frame alternative and null hypothesis, test their hypotheses, and draw conclusions based on class data. This exercise provides beginning students experience with hypothesis testing and introduces them to basic data analysis and experimental error. These lessons are reinforced throughout the semester through a series of exercises explicitly stressing different components of the Scientific Method.

Keywords:  metabolism, scientific method, yeast, respiration, Saccharomyces

University of Delaware (2009)