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Making a DNA model
WH AT I S DNA?
Deoxyribonucleic acid (DNA) is a molecule that contains all the information to determine who you
are and what you look like.
The chemical compound that makes up DNA was first discovered by Friedrich Miescher in
Germany around 1869. In 1953, Francis Crick and James Watson discovered that DNA is shaped
like a ladder coiled into a 'double helix' shape.
The ‘sides’ of the ladder are a linked chain of alternating sugar and phosphate molecules.
The ‘rungs’ of the ladder are attached to the sugar molecules. Each rung is made up of two
chemicals called bases. There are four different bases - adenine (A), thymine (T), guanine (G) and
cytosine (C) and they link together in pairs (A with T, C with G) to form a rung. The order of the
bases and rungs creates a kind of code for the DNA information.
WH AT DO E S DNA DO ?
All living things contain DNA.
Let’s work from the large to the small.
Your body is made up of many different chemicals. An important
group of chemicals is the proteins, which build your body and
help it to function.
Each protein is formed from over 100 amino acids. There are 20
different types of amino acids that can be used to make proteins.
The code in the DNA ladder’s rungs is a recipe for building proteins. Tiny particles called
ribosomes follow the DNA recipe to bind amino acids together and build proteins. Up to 1 000
rungs might be needed to hold the recipe for just one protein.
A group of rungs that carries the recipe for one protein is called a gene. When many genes are
linked together in a DNA ‘ladder’, they form a chromosome.
B UI L D YO UR O WN DNA M O DE L
This model can be fiddly to make, but it’s well worth the effort. You'll learn some great science
along the way!
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WH AT YO U NE E D
To do this experiment you will need the following:
DNA spines and rungs template (from the attached PDF document)
scissors
glue
string (to hang your model up with)
clothes pegs or paper clips.
WH AT T O DO
Stick the rungs to the spines to form the DNA model.
1. Print out the templates of the DNA rungs and spines (stiff card works better then regular
paper). You'll find the link to the DNA model template to the right of this page.
2. Photocopy or paste the templates onto light cardboard. The ideal dimensions for the model
are printed on the template, so you may need to enlarge or reduce the model.
3. Cut out spines A and B.
4. Cut out the rungs.
5. Fold down the tabs so that they are at right angles to the rungs (as shown in the picture).
6. Put glue on one tab of each rung and stick them onto spine A in the numbered boxes. You
can attach the rungs in any order (pointing either way). Wait for the glue to set before
proceeding. You may also want to hold the rung on with a paper clip or clothes peg so it
sticks well.
7. Once the glue is dry, put glue on the other tab of each rung and stick them to the
corresponding numbered position on spine B. This is the tricky part because you'll have to
support both spines while the glue is drying. Once again, this is where pegs will be a BIG
help.
8. When you've completed your model, hang it from the ceiling. To complete the presentation
of your molecule, cut out the Double Helix label that appears with the rungs and hang it from
the bottom of the double helix.
ACKNO WL E D GE ME NT S
CSIRO's Double Helix Science Club would like to acknowledge all our club members who sent in
designs for a double helix model.
We would especially like to thank member Angela Smith whose design served as the inspiration
that led to the construction of this model.
The Helix magazine's former editor, David Salt, fine-tuned the design. We would also like to thank
Dr John Watson, a CSIRO geneticist, for his advice and help.
For more hands-on experiments, join CSIRO's Double Helix Science Club