Just like humans, banana plants have genes and DNA in their cells, and their DNA determines their traits. We cannot see a single cell or the DNA inside of it only with our eyes, but if we remove DNA from millions of cells, we will be able to view it without a microscope, just like it happens with strawberries.
What you need to use to extract DNA from bananas
- Ripe banana
- Teaspoon of salt
- Half cup of water
- Coffee filter
- Resealable zip-top bag
- Narrow wooden stirrer
- Rubbing alcohol
- Dishwashing soap or detergent
- Narrow glass
Place the bottle of rubbing alcohol into the refrigerator or freezer and let it chill for the duration of the experiment.
- Peel a banana.
- Put the peeled banana in a resealable zip-top bag and close the bag
- On a hard surface like a tabletop or kitchen counter, mush the banana in the bag for about a minute until it has a fine, puddinglike consistency and until all lumps are gone. Do not slap the bag or mash the banana too close to the bag’s zip seal. (This could cause the seal to open and the banana to squirt out and make a mess.)
- Fill a measuring cup with a half cup of hot water and a teaspoon of salt
- Pour this saltwater into the bag, and close the bag. Gently mix and slosh the saltwater and mashed banana together for 30 to 45 seconds
- Add a half of a teaspoon of dishwashing detergent or dish soap into the bag. Again, mix around the contents gently. The mixture should not become too foamy
- Place the bottom half of a coffee filter in a clear glass cup. The top part of the filter should be folded over the rim of the glass to keep it in place
- Carefully pour the contents of the bag into the filter and let it sit for several minutes until all of the liquid has dripped down into the cup
- Take the rubbing alcohol from the refrigerator. Tilt the glass and slowly pour the alcohol down the side of the cup until there is a layer that is 2.5 to five centimeters (one to two inches) thick. The alcohol and the liquefied banana need to be kept as separate as possible, so complete this step slowly
- Let the two-layered mixture sit for eight minutes. During this time, the alcohol and the banana liquid layer look cloudy and may have some tiny bubbles in it. The longer it waits, the more defined this layer becomes. This is the DNA pieces clumping together.
- Stick the wooden stirrer into the cup. Spin it in place so the cloudy layers spools around it. Remove the stirrer. Take some of the stringy middle layer on the stirrer and remove it from the cup.
The substance on the stirrer is DNA and we surprisingly have about 60% of the same DNA as bananas!