Brad Hartle, a 4-H STEM educator for Wicomico County at UMES, conducted a strawberry Deoxyribonucleic Acid (DNA) extraction lab using common, everyday materials with 28 seventh graders at The Salisbury School in late November.
During the experiment, Hartle said, students mixed and added a buffer solution made up of salt and water to mashed up strawberries to break up protein chains that bind around the nucleic acids. Dish soap was added to dissolve the lipid part of the strawberry cell wall and nuclear membrane. It was then filtered through a coffee filer to eliminate chunks. Isopropyl alcohol was added to help preserve the DNA and be able to view it.
“The students were skeptical of the experiment at first, but once they started seeing the strawberry break down and the DNA they were full of questions,” said Hartle.
Hartle discussed DNA concepts to the students as the experiment took place. DNA is a double-helix molecule built from four nucleotides: adenine (A), thymine (T), guanine (G), and cytosine (C). If you put all the DNA molecules in your body end to end, the DNA would reach from the Earth to the Sun and back over 600 times. DNA is found in genes contained in chromosomes. There are 46 chromosomes or 23 pairs found in humans; 22 of those pairs look the same for male and female with 23 being XX for females and XY for males. The number of chromosomes varies from species to species, for instance, humans have 46 where as hermit crabs have 254. DNA is found primarily in the nucleus of our cells with small amounts in the mitochondria and chloroplast.
