NewsUpper SchoolAcademics
Biology classes solve DNA mysteries
Feb 18, 2002 8:00 AM
By Stefan Eady - Faculty
Some of life’s mysteries will never be explained, but the Upper School biology classes are working to solve mysteries on the Darlington campus. Students are learning to solve imaginary crimes by using DNA profiling, or fingerprinting, in three classes taught by biology teacher Laura Murray and two honor classes taught by Phil Titus, science department chair.
DNA profiling is often used to analyze evidence in law enforcement cases. The students were given a DNA sample collected from an imaginary crime scene, and five other samples of DNA from possible suspects. Students had already studied the DNA structure and were instructed to use restriction enzymes that cut the DNA. Next, a process known as agarose gel electrophoresis was used to separate the fragments by using electricity. Agarose gel acts as a sieve and separates the fragments by size, so that the smaller ones travel farther than the larger ones. This creates visible bands on the gel after staining. Students then prepared a gel that sits in a buffer solution in the electrophoresis unit, injected the fragmented DNA samples into the gel, and allowed the DNA to run through the gel for a period of four to eight hours. The gels were then removed from the units and stained. Bands that appeared were counted and measured.
To solve the mystery, the bands of each suspect were compared to the crime scene sample. If a match was made, then the criminal could be identified. “Some results were better than others,” said Murray, “We learned by trial and error, but over all the classes really enjoyed it.”
DNA profiling is often used to analyze evidence in law enforcement cases. The students were given a DNA sample collected from an imaginary crime scene, and five other samples of DNA from possible suspects. Students had already studied the DNA structure and were instructed to use restriction enzymes that cut the DNA. Next, a process known as agarose gel electrophoresis was used to separate the fragments by using electricity. Agarose gel acts as a sieve and separates the fragments by size, so that the smaller ones travel farther than the larger ones. This creates visible bands on the gel after staining. Students then prepared a gel that sits in a buffer solution in the electrophoresis unit, injected the fragmented DNA samples into the gel, and allowed the DNA to run through the gel for a period of four to eight hours. The gels were then removed from the units and stained. Bands that appeared were counted and measured.
To solve the mystery, the bands of each suspect were compared to the crime scene sample. If a match was made, then the criminal could be identified. “Some results were better than others,” said Murray, “We learned by trial and error, but over all the classes really enjoyed it.”
