For our second program, G3 focused on being true lab scientists by learning how to extract actual DNA from bananas! The program kicked off with a brief discussion about DNA itself. Do humans have anything in common with a rhinoceros? Or a frog? Or even a tree? The answer to all questions was YES. All life forms contain DNA, which determines what that life will look like and more. In the case of our bananas, the DNA is what tells the banana to be a certain color, or a certain shape, or a certain flavor. Following the instructions from the magazine Scientific American, the G3 scientists discovered that we can extract the actual DNA from bananas using a few household items like dish soap, salt, rubbing alcohol…and of course bananas!
The first step was mashing up the bananas…something that we all enjoyed 🙂 The G3 crew described the bananas, or the banana “slurry” as “just plain gross,” “brownish,” and “looks like vomit.”
We then added salt water to the mush, followed by standard dish washing soap, and then we were ready to strain our banana slurry (to collect just the liquid in a cup). [The soap actually helps to dissolve the membranes of the cell walls that hold the DNA, and the salt helps to draw the DNA strands toward each other.]
The filtering step proved unexpectedly challenging as more than one of our scientists accidentally dropped the banana filter and banana chunks into the cup that contained the strained liquid. Some scientists even had to restrain 2 or 3 times! But we all collected enough liquid to add to our test tubes. The final step was adding a top layer of rubbing alcohol to the test tubes (Head G3 scientist Nicole helped with this part). And then we just needed to wait with fingers crossed to see if we had good results.
While we were waiting, Nicole pointed out the sheet of fun banana facts that each scientist received at the start of the program. In particular, we talked about the fact that most Americans eat only one type of banana: the Cavendish. And due to a fungus that is attacking Cavendish banana plants around the world, in 5 or 10 years the Cavendish banana could very well become extinct! When that happens, we will all be forced to begin eating a completely different kind of banana.
The results started pouring in after only 5 minutes…and every one of the G3 scientists successfully extracted banana DNA! [It should be noted that it even took Nicole multiple practice runs to extract the DNA herself, so clearly our program is full of super star scientists 🙂 ]. Our G3 scientists described the DNA as “white,” “web-like,” and even like a loose collection of “snowflakes.” Of course, many of the scientists wanted to take home their DNA. Coffee stirrers were passed around so that each scientist could scoop out their extracted DNA and place it in a zip-top baggie to take home.
At the close of the program, activity sheets were passed out to all. Each scientist was also able to take home a copy of the experiment instructions, as well as the sheet of fun facts about bananas. Many of the banana facts were obtained from the Chiquita banana web site. I wonder what we’ll be doing next!…