Build your own DNA molecule from sweets


Procedure: (Download instructions)

1. Take the two candy cords - assign one colour to represent the pentose sugar molecules and the other to represent the phosphate molecules. Cut the candy cords into 2 - 3 centimetre pieces.

2. Using the needle and thread string half the candy pieces together lengthwise alternating the two colours to form a chain.

3. Repeat step 2 with the remaining half of candy pieces to form a second chain of the same length.

4. Lay the two chains down side by side so pieces of the same colour are opposite one another.

5. Count the number of pentose sugar molecules you have in one chain (you should have the same number in both chains). Obtain this number of cocktail sticks. These represent hydrogen bonds that hold the base pairs together.

6. Divide the sweets into four different colours. Assign names to the each of the four colours to represent the nucleotide bases - adenine, cytosine, guanine or thymine.

For example:

adenine thymine
cytosine guanine

7. The bases have to be paired up on the cocktail sticks. Adenine always pairs with thymine and guanine with cytosine, so make sure you get the right colours matching.

8. Push each end of a cocktail stick into candy pieces representing pentose sugar molecules lying opposite one another - the cocktail sticks should join the two chains together so they look like the rungs of a ladder.

9. Hold the end of each chain and twist slightly to get the double helix effect for your DNA model.

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