Biology students participate in DNA extraction lab

On Friday, January 25, students in Mrs. Cloud’s biology classes extracted DNA from strawberries. This lab demonstrated that the substance containing the instructions to make and sustain living things is present and can be isolated from its cells. 

As any good crime scene investigator knows, the first step to DNA analysis is having the ability to retrieve and isolate DNA. DNA can be found in the cells of every living, or once-living thing. It provides the instructions for building and operating all living things. The nucleus of a cell contains chromosomes. Chromosomes are made up of DNA. DNA is short for deoxyribonucleic acid; it is a special chemical that carries the hereditary information in almost all living things.

The DNA tells the cell how to work and which particular characteristics it should have. A section of DNA that tells the cell to display a certain characteristic, or produce a certain particular chemical is called a gene. In the extraction experiment, the reagents used allow us to separate the DNA from the cell.

First the physical mashing of the fruit breaks open the plant’s cell wall. The soap extraction solution ruptures the outer cell membrane, while the salt help separate the DNA from other cellular molecules, such as carbohydrates. The process of cooling helps protect the DNA from enzymes that normally do not bother the DNA because the DNA remains separated from the rest of the cell by the nuclear membrane. The cold temperature slows down these enzymes. Filtering removes most solid matter in the mixture. When the cold isopropyl is added, it floats on top because of the difference in densities of the materials. DNA is not soluble in isopropyl and precipitates out of the solution, visible as white strings.

Check out what SPCHS Class of 2022 members Grace Belk and Avery Culbertson said about participating in the lab below!

Photos from the lab can be viewed here.