An easy and fun science experiment to extract DNA from a banana that can be done at home with a few household ingredients. Have fun!
A ripe banana, half a cup of water, 1 tsp of salt, Ziploc bag, washing up liquid, rubbing alcohol, coffee filter or piece of muslin, tall glass, thin wooden stirrer.
#1 – Pop your bottle of rubbing alcohol in to the freezer or fridge whilst you do the rest of the experiment. Peel the banana and put it in the Ziploc bag. On a hard surface smoosh the banana with your hand until all the lumps have been squeezed smooth. Be careful not to squeeze too near the zip in case it splurges out.
#2 – Warm half a cup of hot water and stir in the salt until it has dissolved. Pour the salt water into the bag and sloosh it around for a minute. Add a tiny (half a teaspoon) amount of washing up liquid and slosh around again, but don’t let the mixture get foamy.
#3 – Put the coffee filter or muslin over a clean glass and secure in place (or use a funnel). Pour the bag mixture into the filter and let it sit for a few minutes, until all the liquid has seeped through. Once all the liquid has run out you can chuck the filter and any remaining goo in the bin.
# 4 – Take the rubbing alcohol from the fridge/freezer and tilt the glass, whilst slowly pouring in the alcohol. You don’t want the liquids to mix, so another way of creating layers is to pour the alcohol slowly over the back of a spoon. What ever is easiest for you! Keep pouring until you have 1-2 inches of rubbing alcohol.
# 5 – Let the concoction sit for 8 minutes. Observe what is happening in the glass. Are bubbles forming and clumping together? After 8 minutes stick the stirrer in the middle of the glass and twirl it around (like spaghetti on a fork). Remove the stirrer gently and it should lift up some of the gooey stringy clouds with it. These strings are the bananas DNA!
The DNA has been extracted from the banana by the washing up liquid breaking up the cells membranes, the salt helps separate the DNA from the cells. Because DNA can’t dissolve in alcohol the rubbing alcohol causes the clumps of DNA which have been broken out of their cells to clump together, which is what you end up with on the stick!
Have fun with this experiment and let us know your results!