Do you know you can observe DNA? Although it is housed within our microscopic cells, DNA may simply be extracted from strawberries. With elements available in your kitchen, you will extract this immense molecule present in all living beings and observe it, without a microscope.
You will need:
- 3 strawberries
- Some salt
- Dishwashing liquid
- 10 mL of water
- A knife
- A spoon
- Two transparent glasses
- Ziploc bag
- A marmelade jar with a lid
- A sauce-pan
- Rubbing alcohol
- A coffee filter
From 8 years old
Difficulty : experienced
This experience requires the help of an adult
Burning alcohol cannot be drunk, This substance is a poison. Drinking just a small amount can result in fatal consequences
Let's experiment
NB: place the rubbing alcohol into the fridge prior starting the experiment
In a glass, add 5 drops of dishwashing liquid and,
10 mL of water.
Then add a pinch of salt and mix gently with a spoon until the salt is completely dissolved.
With a knife, cut the strawberries into small pieces. Get the help of an adult.
Put them into the Ziploc bag, and squish them with your hands. Pursue until you get totally crushed strawberries.
Add your strawberry puree to the soap-based solution and mix well with a spoon.
Fill your glass jar with your preparation and close the lid tightly. Check that it is perfectly closed.
In a saucepan, heat some water to 60 ° C and place your jar in the hot water for 5 minutes.
Using a coffee filter and a funnel, strain your preparation into a clear glass. You have to get a reddish liquid.
Then ask an adult to pour 50 ml of cold alcohol into a glass jar. Slowly pour the filtered strawberry solution while mixing with a spoon.
TADA, white filaments appear! You have successfully extracted DNA from several thousand strawberry cells.
Understand the experiment
What is DNA?
DNA is a huge molecule that contains all the information about how the livings things look likes and how they function. Size, color, shape, growth, immune system, it’s all defined by our DNA. In reality, every piece of DNA contains important information. Besides, this gigantic molecule is protected in the nucleus of our cells.
Did you know?
In humans, DNA can be up to two meters long.
Why does the dishwashing solution make it easier to extract DNA?
As you know, DNA is present inside our cells. Cells are delimited by a membrane that retains all essential elements allowing the cell to function and live. It controls what enters and what leaves it. This membrane is flexible and consists of a double layer. Molecules located inside the double layer doesn’t like water, but interact with fat. While the outside of the membrane interacts with water. This membrane is easily destabilized by soap molecules whose properties are similar. Soap molecules infiltrate the membrane and disintegrate it. Which frees up its content.
As for salt, it breaks the links between DNA and proteins linked to it. This process makes it easier to “precipitate” (insolubilize) DNA when you pour the solution into the methylated spirits.
Did you know?
If you could assemble the DNA of each of your cells, the length obtained would be twice the diameter of the solar system.
Why is it easier to extract DNA from strawberries than from another fruit?
Strawberries are rich in pectinases, an enzyme that breaks down proteins. This enzyme makes it easier to release DNA, and prevents proteins from cutting it into small pieces. They are so effective that they are used to tenderize meat.
In addition, each cell in the strawberry contains eight copies of DNA, which allows for much more to be extracted. It is said that the strawberry is an octoploid. For sake of comparison, humans have only 2 pairs of chromosomes. They are diploids.
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