Academics, Upper School

Students Genetically Engineer Bacteria

Seniors in Advanced Biology recently completed a bacterial transformation lab utilizing the same process scientists use today to synthesize insulin and other complex proteins.

“In this class we are approaching genetics as a tool for students to understand diseases,” says Biology teacher Kathryn Wallace. “Diabetes is the perfect example because it is relatable to most students, and we can showcase how science has helped create a solution that previously didn’t exist.”

As Kathryn notes, proteins have complicated structures and cannot be created independently in a laboratory environment. Previously, insulin for diabetics was made by extracting the pancreas from a cow or pig. Today, scientists can transform bacteria with snippets of DNA called plasmids (a genetic structure in a cell that can replicate) containing a gene of interest, which makes the bacteria produce a specific protein such as insulin.

The technique is simply known as transformation. For the lab, students took a bacterium and introduced two plasmids, one containing a gene with ampicillin resistance, and another with a gene that causes a color change. Then, they combined the plasmids with bacteria cultures and placed the mixture in an ice bath for 15 minutes.

“When you cool down the mixture, it causes the plasmids to settle near the bacteria,” explains Kathryn. “After the ice bath, we give the mixture a heat shock. When bacteria are stressed, they tend to grab things from the outside environment and pull them in. In this case, the bacteria snares the plasmids, and now it has that new DNA inside.”

The end result for students who correctly completed the lab was a petri dish with spots of blue bacteria, a sign that the bacteria was successfully genetically engineered.