Extract: to draw or pull something out (especially from another material).
Gene: a region of DNA that instructs the cell on how to build protein(s). As a human, you usually get a set of instructions from your mom and another set from your dad... more
Molecule: a chemical structure that has two or more atoms held together by a chemical bond. Water is a molecule of two hydrogen atoms and one oxygen atom (H2O)... more
All living things, bananas and people included, pass on information from one generation to the next using the same basic material, DNA. Within every living organism, most cells contain a complete set of DNA instructions. The information in DNA tells our bodies how to develop, grow, and work. It also controls many of the features that make an organism unique.
These instructions are in segments of DNA called genes. Genes, along with other parts of our DNA that turn genes on and off, hold information for how our body develops and functions. They produce molecules called proteins that do most of the work in the body. Variants of genes, called alleles, are responsible for differences in hair color, eye color, and earlobe shape.
All of these instructions fit within tiny packages within our tiny cells, so that is all way too tiny for anyone to ever really see or touch, right? Well, not entirely. Because DNA is in every cell, there is a lot of it in an organism. If you took all of the DNA out of some middle-sized organism (or part of an organism, like a piece of fruit), you could see and even touch DNA. We will use common household products to break apart the cells in a banana and extract out the DNA. While you may know of the double-helix structure of DNA, you can't see that structure with the naked eye. So when seeing it without a high-powered microscope...what does DNA look like?
Watch biologist Melissa Wilson Sayres as she shows you step-by-step how to extract DNA from a banana.
(Teacher & student packet is available.)
You may understand that mashing a banana can break cells apart and help break apart cell walls, but why was all that other stuff added? And how did we get inside the cells and get the DNA to stick together?
Let's think of three of the main items we added to the bananas.
Banana and Strawberry image by Ralph Daily via Wikimedia Commons.
Melissa Wilson Sayres. (2016, April 19). Seeing DNA. ASU - Ask A Biologist. Retrieved May 6, 2021 from https://askabiologist.asu.edu/activities/banana-dna
Melissa Wilson Sayres. "Seeing DNA". ASU - Ask A Biologist. 19 April, 2016. https://askabiologist.asu.edu/activities/banana-dna
Melissa Wilson Sayres. "Seeing DNA". ASU - Ask A Biologist. 19 Apr 2016. ASU - Ask A Biologist, Web. 6 May 2021. https://askabiologist.asu.edu/activities/banana-dna