As part of their A-level Biology work, students are expected to carry out a number of experiments that will comprise part of their grade, called the Practical Endorsement. This replaces the traditional coursework aspect of Biology and is made up of a series of experiments in twelve skill areas.
One of these skill areas is in regards to chromatography and electrophoresis. Electrophoresis is the process by which DNA fragments are separated according to size, under the influence of an electrical current. Although in wide use in universities, it has previously not been possible to carry out this experiment in school but it regularly occurs in exam questions.
On Tuesday 6 March, as part of the University of Leeds “Festival of Science”, Allerton Grange students were fortunate enough to be selected for a roadshow about “How we use DNA?” and were able to experience gel electrophoresis first-hand.
The process involved students taking small, accurate, volumes of the specimen DNA and introducing them into separate wells in the agar gel blocks. They did this using a Gilson pipette (another first for them) and could easily convert the small volumes (microliters) into more recognisable units (millilitres). Once they had completed loading their gels into the electrophoresis tank, they were able to explain how the charge on the DNA molecules would interact with the electrical current to induce movement. The neon/fluorescent dyes that had been added to the DNA samples enable the students to easily identify the different genes and their meaning for the patients.
13D/Bi1 were the first to have a go, followed by 13A/Bi1, and they managed to successfully use electrophoresis to identify which patients were carrying one, or both, of the human tumour suppressor genes, BRC-1 and BRC-2. Every single student correctly identified which patients were at risk for developing breast cancer and could also suggest treatment options. The University of Leeds students were impressed with our A-level students’ knowledge of this topic, as shown in the 100% score for both groups in the accompanying quiz.
Having this hands-on experience of quite a complex and difficult procedure will prove to be invaluable to our students and we are hopeful that there will be another electrophoresis question in the upcoming exams.