Minisink Valley teachers continue to be imaginative in adapting classroom science experiments to experiments that can also be done at home, reinforcing hands-on science education doesn’t stop during a pandemic.
Kimberly Jordan’s College Biology 101 class, offered in partnership through Orange Community College, recently reinforced a lesson about DNA with her “Extraction of DNA from Strawberries” lab.
DNA, or deoxyribonucleic acid, is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.
Using items found in any household kitchen, students took dish detergent, salt and water to break apart strawberry cells. Because of the special characteristics of strawberries, it’s possible to extract, isolate and observe a strawberry’s DNA in a matter of minutes without an electron microscope.
While other fruits are soft and just as easy to pulverize, strawberries are the perfect choice for a DNA extraction lab because they yield more DNA than other fruits, contain enzymes called pectinases and cellulases that help to break down cell walls and are “octoploid,” meaning that they have eight copies of each type of DNA chromosome.
An experiment both for in-class and at home
Students, whether they were participating in the class or remotely, first ground up the strawberries by hand using the solution, strained them and collected the juice. This process allowed the DNA to be free of the nucleus.
To extract the DNA, each part of the extraction mixture plays a part. Soap helps to dissolve cell membranes. Salt is added to release the DNA strands by breaking up protein chains that hold nucleic acids together. Students then collected the DNA by pouring rubbing alcohol (DNA isn’t soluble in rubbing alcohol) into the strawberry liquid.
Later, students collected the DNA (which looks like clear nasal mucus) using a coffee stirrer. This was stored in a small tube to take home to share with their family and friends.
“I wanted to showcase how teachers are keeping their students active with science experiments using basic kitchen materials,” she said “The kids had a great time. Whether in-class or home, science doesn’t stop.”
See more photos on the district’s Facebook page.