On November 7, 49 AP Biology students from SAR HS visited the Dolan DNA Learning Center in Cold Spring Harbor, NY, where they performed two labs: A restriction analysis and a bacterial transformation.

The restriction analysis lab involved cutting up viral DNA with the bacterial enzymes HIND III and Eco R1. These enzymes are a bacteria’s natural defense against bacteriophages (viruses which attack bacteria). But researchers later discovered that these enzymes can be used by scientists as “scalpels” to cut DNA in precise ways. The students used these two enzymes to cut DNA from a virus called “lambda” and then they separated the fragments using a technique called gel electrophoresis. After the fragments separated on the gels, photographs were taken of the bands of DNA. The photos were placed on the Dolan DNA Learning Center website to be downloaded and analyzed by the students back home and they will ultimately be incorporated into the students’ lab reports.

In the second experiment, the students used small circular strands of DNA called plasmids. These plasmids contain the genes for antibiotic resistances. Using a technique called transformation, the students inserted those plasmids into bacterial cells and those bacteria were then grown on various media. Although the students only succeeded in inserting plasmids in about one in a million cases, when working with many millions of bacterial cells, the procedure results in numerous colonies that are now, as a result, antibiotic resistant. The plates with the bacteria were brought back to school and allowed to grow for two days before the students counted the transformed colonies.

The students were quite successful in performing both experiments. The Dolan DNA Learning Center also has some museum displays that are quite interesting, including a model of the model that Watson and Crick built when elucidating the structure of DNA in 1953.