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DNA EXTRACTION
Activity Pack
Description:
Learn how genetic information can be extracted
so it can be studied by scientists
Duration of Activity:
15 mins approx.
Age:
7yrs+
Topic:
Molecular and Cellular
Key words:
DNA, Double Helix, Gene, Alleles, Adenine, Thymine, Cytosine, Guanine,
Nucleotides
Resources:
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Related Activities:
DNA Bracelets, Zebrafish in Medical Research
Instructions and Equipment List
Activity Worksheet
Cell-Chromosome-DNA Sheet
MRC Lab Scale/DNA Poster
Activity Evaluation Poster - Children
With thanks to MRC Human Genetics Unit at the University of Edinburgh
DNA Extraction
Instructions and Equipment List
Key messages
»» Everyone’s DNA is different - DNA is what makes you unique
»» DNA contains all the instructions your body needs to live
»» DNA contains the instructions for life for all living organisms every plant and animal
What MRC Scientists do?
»» Study DNA to learn about human, animal and plant health.
»» Extract DNA samples from a person who has a disease and compare it with a person who does not to see if there are
any differences linked to the illness. This is called genetic research.
Activity overview
Learn how genetic information can be extracted from peas so it can be studied by scientists
Steps
1. Introduce DNA and its function while participants put on gloves and safety glasses
2. Pass sound a bowl of dried peas and invite participant to examine this is the source of the DNA
3. Get a participant to measure 30ml of washing up liquid into the measuring jug. Use funnel to add 50-100ml of prepared
cell extract
4. Follow instructions on worksheet – each participant will have their own test tube with mixture to warm in hands for 5
minutes – set timer.
5. Proceed to step 4 helping participants to add pineapple juice, salt and finally surgical spirit.
6. Invite participants to shout out when they start to see DNA.
7. Collect the tubes back from the participants and dispose of waste solution.
Important notes
»» Quantities are sufficient for a group of 5 participants
»» Keep flasks of cell juice and surgical spirit safely out of reach
»» A double helix model will help explain the structure of DNA
Suggested Script and background information
The best way to gauge understanding of participants is to ask them questions like
»» Has anyone here heard of DNA?
»» Can anyone tell me what DNA is?
Every living thing contains DNA. It is the unique set of instructions that tells a seed how to grown into a plant or a baby into adult.
Everyone’s DNA is different. DNA controls the colour of your eyes, skin and hair.
DNA is wrapped tight inside the nucleus of every cell that builds a living thing. DNA is coiled tightly like thread and wrapped and
squished into bundles that scientists called chromosomes. Usually the DNA is packed so tightly it is impossible to see, but today
you are going to take the DNA out of peas.
You are going to get to see what a pea’s DNA looks like.
»» Pass around the bowl of dried peas.
Before we can get the DNA out we need to mush the peas up a bit.
Here is some cell juice made fresh this morning – this is a mixture of water and peas all mashed up in a blender.
»» Select participant to add 30ml of washing up liquid to the measuring jug– then use the funnel to pour 100ml of cell
juice into the measuring jug and gently mix.
»» Swirl the liquid to mix the soap in try not to let it get bubbly.
»» Get participants to follow the protocol on work sheet.
»» Pour 10ml into each participant tube and the remainder into a large cylinder
»» Give a tube to each participant – make sure the lid is on! Ask them to hold it in their hands for five minutes to warm the
mixture up.
Explain that the warmth helps the soap break the cells apart.
»» Set a timer for 5 minutes. – Use this time to discuss DNA or combine with Zebra Fish Activity Plan.
»» Proceed to step 4
The soap and heat have done their job to break the cell apart and release the DNA.
Now invite participants to use pipettes/droppers to add pineapple juice – this will pull away proteins attached
to the DNA.
»» Adding a pinch of salt helps the DNA now outside the cell to join together.
»» Use the second funnel to pour 50 ml of surgical spirit into a measuring jug and then tilt the tubes and pour the surgical
spirit down the side so that it forms a layer on top of the mixture. You will need 10ml to match the volume of pea
extract already in the tube – but keep pouring until there is approximately the same amount of both liquids (20ml
total).
Talk to the participants about structure of DNA (see below) while you wait for the white strands of DNA to
move up and out of the cell mixture into the layer of alcohol.
DNA normally stays dissolved in water, but when salty DNA comes into contact with alcohol it clumps together and rises into the
alcohol.
Ask them to shout out when they start to see DNA. You can show them an example tube from earlier so they know what to look
for.
Further information on DNA structure
DNA stand for DeoxyriboNucleic Acid and is made of just four chemical bases that you can think of as building blocks. These are
called adenine (A), cytosine (C) and thymine (T) and guanine (G). These bases are arranged in different orders to give each cell in
the body a code that tells it what to do. It’s a bit like using the letters of the alphabet to spell words, DNA uses A, C, T and G to
spell out instructions in groups called genes.
DNA has two strands that wrap around each other in a shape called a double helix. To help DNA stick tightly together the bases
match up in pairs. A always partners with T and C always joins up with G. The spiral shape lets DNA wind itself up tight and small.
There is about 2 metres of DNA inside each cell.
The double helix shape helps DNA to fit lots of genes inside cells. Genes are packaged up in bundles of DNA called chromosomes.
The chromosomes sit in the nucleus of a cell. Every time a cell divides, DNA makes a copy of itself, this copy tells the new cell what
to do. When the new cell divides it will make another copy of DNA. Cells divide to help you grow and to replace old cells.
Further information on DNA and chromosomes
Every cell in our bodies (except red blood cells) carries all our genetic information packaged tightly into chromosomes and every
time we grow the chromosomes are copied and passed onto the new cells.
Cells carry all of the genetic information needed to make an animal, or human, or plant. Women have 22 pairs of chromosomes
and two X chromosomes. Men have 22 pairs of chromosomes and one X and one Y chromosome.
Scientists study chromosomes to learn about human health.
For further information visit MRC Research
DNA Extraction
Equipment List
Staging
This activity is best conducted on tables that participants can stand or sit around
Required
»» Worksheet – one per participant or per group
»» Clear tubes with lids that can accommodate more than 20ml -one per participant
»» Pairs of gloves - one per participant
»» Pair of safety glasses - one per participant
»» Large flasks x 3 (pea extract /Surgical Spirit/waste solution)
»» Measuring Jug large X 2
»» Jug small x 1
»» Funnel x 2
»» Bowl container x 2 (peas and salt)
»» Pipettes or droppers for dispensing pineapple juice
»» Timer
»» Cloths and kitchen towel for spills
»» Ingredients: Peas, washing up liquid, pineapple juice, salt, surgical spirit
Optional
»» Double Helix Model
»» Cell-Chromosome-DNA Sheet
»» MRC Lab Scale/DNA Poster
»» Lab coat - one per participant
»» Activity evaluation poster - children
DNA EXTRACTION
Worksheet
Every living thing contains DNA. Plants, animals and
people all carry DNA deep inside their cells, it is the
unique set of instructions that tells a seed how to grow
into a plant or a baby into adult.
DNA is wrapped tightly inside the nucleus of every cell
that builds a living thing so usually it is impossible to see,
but today you are going to take the DNA out of peas.
First you need some cell juice-the Scientist team made
this earlier. Cell juice is a mixture of mashed up peas and
water.
1. Add 30ml of washing-up liquid to the cell juice
and swirl it gently. The soap helps to burst open
the cell membrane to break the cell apart so that
the DNA can roll out of the nucleus.
Everyone’s DNA is different. DNA controls the
colour of your eyes, skin and hair. The information
in your DNA also controls the cells in your body.
Sometimes there are bits of information missing, or
it is a bit scrambled, and this can cause illness.
Scientists study DNA to learn about human health.
For example in research, scientists often compare
DNA from a person who has a disease with a person
who doesn’t to see if there are any differences and
whether they are linked to the illness. This is called
genetic research.
Your DNA comes from your parents. You inherit
half from your mum and half from your dad; this
mixture is what makes you unique. The same DNA is
present in almost every cell of your body.
2. Pour 10ml of cell juice into a tube.
3. Hold the tube in your hands for five minutes, this
will warm the mixture up and help the soap to do
its job.
4. Add three drops of pineapple juice. The acid
in the pineapple juice pulls away any proteins
clinging to the DNA.
5. Add a pinch of salt to the tube. The salt helps the
DNA that has escaped the cells to stick together.
6. Next you are going to add surgical spirit to the
mixture. The alcohol in the surgical spirit will
separate the DNA from the mixture but you need
to pour it in slowly. Tilt the tube and pour the
alcohol down the side so that it forms a layer on
top of the mixture. Keep pouring until there is
the same amount of both liquids.
7. Watch as white strands of DNA move up and out
of the cell mixture into the layer of alcohol. DNA
normally stays dissolved in water, but when salty
DNA comes into contact with alcohol it clumps
together and rises into the alcohol.
MRC
C
A
G
T
G
T
x chromosome
DNA FACTS
DNA stands for deoxyribonucleic acid
Human DNA has about 3 billion bases
DNA is in every cell except red blood cells
There are about 2 metres of DNA inside each cell
About 76% of your DNA is the same
as the DNA of a zebrafish
CELL - CHROMOSOME - DNA
Chromosome
Cell
DNA
DNA FACTS
DNA stands for DeoxyriboNucleic Acid
DNA is in every cell except red blood cells
x chromosome
There are about 2 metres of DNA inside each cell