Washington Middle School eighth graders became “real” scientists by working hand-in-hand with scientist Dr. Mike Darwin Yerky, an outreach coordinator from Cornell University. They learned how to analyze DNA samples during Kay Eklum’s AT Science class by solving a simulated paternity case during a daylong lab by using gel electrophoresis to separate and analyze DNA samples.
To prepare for Dr. Yerky’s visit, students studied the DNA molecule in detail including that DNA stands for Deoxyribonucleic acid. DNA is made up of long chains of nucleotides and each nucleotide has three parts – a deoxyribose sugar, a phosphate group and a nitrogenous base. All living things have the same four bases – adenine, guanine, cytosine and thymine. Students looked at examples of DNA fingerprints and matched people based on the bands of DNA they had in common.
With Dr. Yerky, students learned about the process used to separate DNA, which is called gel electrophoresis. First, they cut the DNA using restriction enzymes. DNA is a negatively charged particle, so when it a sample of cut DNA is placed in an electrophoresis set up, the electricity causes the negatively charged DNA fragments to move towards the positive end. The smaller fragments move quickest, because they are small. The larger fragments are left behind and were left with a DNA fingerprint.
“It is important to bring other teachers into the classroom because it’s like an in-school field trip,” said Mrs. Eklum. “Students learn in different ways, sometimes a presenter can spark a student’s interest or help them learn something better than their regular teachers can. It is also good for students to see adults working together to teach them a topic.”
The students enjoyed the new experience but many found it challenging to work at such a high level for so many hours. However, exercises like this one prepares them for what they can expect in some college-level science labs.
“I’ve never done an all-day lab like this,” said Washington eighth grader Andrew Sisson. “It was really interesting and fun.”
Dr. Yerky also brought sample of fish cells for students to create “DNA Necklaces.” After extracting the DNA from the cells, students took the fish cell samples, separated the DNA into long strands by using a mixture of salt and ethanol, and spooled them onto special tools. Once they extracted the DNA, students placed it in a microtube and attached colored yarn to make their DNA necklace.