How could you extract the DNA

from these kiwis?

What problems might you face?

Overview

In order to extract DNA from plant cells you need to be able to break through the cell wall and membranes of the

cell

Thinking Points• How can we do this in the

laboratory?• How well will you be able to see the

DNA?

DNA is found in every cell of every living thing,

including kiwi fruit, but the trick is how to get it

out of the cells.

Part of the problem is getting the DNA out of the cells and then you

also have the problem of disentangling the DNA from the protein inside

the cells.

Extracting DNA from cells

Equipment:

-Kiwi fruit-Salt-Washing up liquid-Water-2 x 250cm3 beaker-Knife and white tile-Water bath-Stopclock-Iced water-Ice cold ethanol-Filter paper

Aim: Investigate how to extract DNA from a kiwi

• Safety goggles on

• Hair tied back

• Ethanol is flammable – keep away from naked flame

• You are using sharp knives – be responsible

• Responsible attitude

• Follow instructions on the first time of giving!

Make a solution of • teaspoon of salt•6ml washing up liquid•1 of water

In a plastic cup

Chop up the kiwi fruit and add to the solution you have just made

Chopping the kiwi breaks open the cell. The solution of detergent and salt strips away the cell membrane and

allows the contents to escape

Make a water bath up to 60oCStir the mixture (DONT LET IT

FROTH!)

Put into the water bath for 6

minutes

Remove the beaker from the water bath. And put into a tub of ice for 3 minutes

Pour the mixture into

a funnel lined with

filter paper

Collect 50cm³of the liquid in a

clean beaker

Drizzle ice cold ethanol down

the inside of the beaker

When you pour the cold ethanol onto the green layer you make the DNA dissolved in the water layer at the bottom turn into a solid, this is because the DNA cannot remain in

solution in ethanol.

You should be able to see a white layer.

Try scooping out the DNA using

the piece of wire

What you should have seen…

DNA Extraction

Complete the cut and stick activity.

The pictures are in order but the instructions aren’t!

When you’ve finished, try the review activity.

Review - What’s inside our nucleus?

1. Label as much of this diagram as you can

2. What words would you associate with genetics other than those you’ve labelled the diagram with?

Back to DNA Discoveries

Try the questions on experiments showing that DNA is the genetic material

.