Students from Serra Catholic, along with their teacher Cara DeSalvo, explored gene regulation at a recent Carnegie Mellon University Department of Biological Sciences outreach event. Using the knowledge that bacteria cells, such as E. coli, use glucose as a carbon source and that the enzyme, β-galactosidase, aids in the conversion of disaccharide lactose to glucose and galactose monomers, the students monitored two bacterial cultures and removed samples at regular intervals to assay for β-galactosidase. Then, students predicted and observed the effect of different sugars on the intercellular levels of β-galactosidase using orthophenolnitrate as a substrate. When present, β-galactosidase will cleave the bond in orthophenolnitrate resulting in two products, galactose and nitro-phenol. Students used a spectrophotometer to measure the amount of nitro-phenol via absorbance. Therefore, the students demonstrated that certain small sugar molecules regulate the expression of E. coli’s lactose genes.
Biology undergraduate and graduate students served as teaching assistants and guided participants through the experiment.
Article initially published at http://www.cmu.edu/bio/outreach/index.html