How to Extract DNA from a Banana
What makes us like we are? What colour hair, eyes, body shape, whether we are male or female, actually human and not a dog? Well, it’s all coded in our DNA.
DNA for kids to understand can be a challenging subject it’s abstract it’s not like we can see it right? Well you can’t see the actual structure easily you need an electron microscopic to do that but you can see the strands easily that makeup DNA you can extract it from a banana. Here’s a simple experiment to extract DNA so that your child can see the strands from inside the cells.
What is DNA
DNA or deoxyribonucleic acid is the material inside the cells of a living thing (apart from some viruses which have RNA instead) that carry the genetic code for making the living thing.
The DNA is divided into small sections called genes and each of these genes carries the information that is needed for how things look and even how things work.
DNA is found in each of the cells of an organism, in most it’s as it’s a complete set with 2 strands joined together with the bases. However, in female and male reproductive cells the DNA is split and that is passed to the offspring to join together to code for the new organism.
As the mixing of the DNA happens this is how variation happens within a population and why we don’t all look exactly the same.
If you would like to make a model of DNA then we enjoyed making this Candy DNA Model from Science Sparks.
Although you won’t be able to see this structure you will be able to collect the DNA and show that it is string-like with this simple science experiment for kids.
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Extracting DNA with Kids
DNA can easily be extracted from soft fruit like bananas as they are easy for kids to mash and puree which breaks some of the cell structures and therefore easier to extract the DNA to view.
We used a banana because that was the softest fruit we had in the house – however, pineapple, strawberry, and kiwi work really well too.
Adult supervision will be needed when it comes to using Isopropyl alcohol
Materials needed for DNA Extraction from a Banana
We have provided instructions for extraction with a Chemistry set, we have this set (US Amazon, UK Amazon) if your child prefers and you have a set handy or with simple kitchen equipment.
Common Materials
- Knife
- Chopping board
- Sieve
- Bamboo Skewer
- Banana
- Isopropyl alcohol (Rubbing Alcohol) available from the Chemist or on Amazon in the UK a VERY strong vodka may work but we didn’t try that in this experiment
- Warm water
- 1 tea spoon of salt
- Washing-up Liquid (Dish Soap)
Materials from Chemistry Set
- 2 x Beaker or Beaker and Conical Flask
- Stirring Road
- 2 Test tubes
- Test Tube Holder
Materials from The Kitchen
- 2 glases
- Plastic bag which seals
- Fork
Preparation
You will need to place the Isopropyl alcohol into the freezer as you need cold alcohol for this experiment.
How to Extract DNA from a Banana
Make sure you have a clear and clean workspace. Wear safety glasses whilst conducting the experiment.
1. Cut up half a banana into slices and then quarter these slices.
2. Either place the banana in a beaker or small sealable plastic bag. Then smush it to mush. Use a fork, stirring rod, or similar in the beaker and your hands on the outside of the plastic bag.
3. In either a separate beaker or glass prepare a solution of warm water and dissolve in the teaspoon of salt. Once it’s dissolved add in around 5 small squirts of washing-up liquid and stir.
4. Pour the mixture into the mushed-up bananas and stir thoroughly so that you have a gooey liquidy banana solution.
5. Using the sieve place above a glass or your beaker you used for the water mixture and pour in the banana mixture letting the liquid go through but not the clumps of banana that you may still have left.
6. Now half fill and empty glass or test tube with the solution.
7. Get an adult to fill a test tube about 1cm full or a glass 1/4 full with the Isopropyl alcohol from the freezer.
8. Now gently pour down the side of the test tube or glass. You may find this easier to do with a pipette if you have one available.
9. Observe the layer of white that appears above the banana liquid. Take the skewer and place it into this and bring it out.
That snot-like substance is strands of DNA you can use a microscopy and magnifying glass to see the strands in more detail – full instructions on how to prepare it can be found here (under what does Strawberry DNA look like) as well as instructions for how to extract DNA from a strawberry.
The process explained
DNA is contained within the nucleus of the cells within the banana to extract it we need to break the cells up and the cell membranes so that the DNA is free in the liquid.
Although mashing the banana breaks up some of the cells we need the salt and the soap to fully break down the cell membranes and allow the DNA to form in the liquid.
The soap breaks the cell walls and membranes and then the salt traps the DNA and means that we can actually see it.
The Isopropyl alcohol is needed as DNA doesn’t mix with it and instead, it forms a layer of DNA that we can then put the skewer into and remove to examine.
Where does this fit in Science?
It’s a fun experiment for kids, but where does it fit in science learning?
Here are some ideas of where you could do this experiment.
Learning about Dinosaurs
If you are learning about dinosaurs and the question comes up but could we recreate them now then DNA is essential. Maybe you’ve watched Jurassic Park and seen then extract DNA from the mosquito, you can now see what would have been extracted too.
When Learning about Reproduction
Whether it’s plants or animals a good time to quickly introduce DNA is when talking about sexual reproduction and the female and male sex cells combining to make offspring.
Check out our plant reproductive organ experiment to explore this further.
Evolution, Inheritance and Natural Selection
If you are covering evolution and inheritance then this is a great time before you start to delve into passing characteristics to offspring and mutation to carry out this experiment.
More Fun Experiments for Kids
Are you looking for more fun and simple experiment for kids check out these ideas below
