Aldrich), which utilizes a colorimetric readout to measure lactate concentrations. This module exposes students to standard sterie techniques by teaching them to culture L casei in both solid agar plates and liquid media. They also learn about the concomitant action of a series of enzymes in a metabolic pathway that converts glucose into lactate (Figure 18). These pathways are conserved in higher organisms and form a significant component of college level biochemistry courses, thereby providing students an early introduction to the topic of metabolism.