DNA contains the genetic code that make us who we are. Formally known as deoxyribonucleic acid, DNA is made up of the four chemical bases adenine, cytosine, guanine and thyamine paired together and attached to phosphate and sugar molecules. These chemical compounds arrange themselves in duel strands known as a double helix. School students can easily turn this ladder-like, twisted structure into a science model project using simple materials such as beads and straws.
- Skill level:
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Things you need
- Straws in four different colours or patterns
- Fishing line
- Beads in two different colours/sizes
- Pipe cleaners
Provide each student with 18 beads in one colour and 16 in another. The 18 beads will represent the sugar and the 16 will be the phosphate. Make sure the students know which is which. For example, 18 red sugars and 16 blue phosphates.
Cut two pieces of fishing line to approximately 12 inches per student. Adjust the size for the beads. Have the students start with the sugar colour bead and string both kinds, alternating colours. Each piece of line should have 17 total, with nine sugar beads and eight phosphates. Do not push the beads all the way together. Leave a centimetre or so of space in between to tie on the bases later. Tie both ends to the top and bottom beads.
Cut the straws into 1 1/2-inch sections. Assign different colours for each of the bases. For example, adenine will be purple, guanine will be yellow, cytosine will be white and thyamine will be white with a red stripe.
Cut pipe cleaners into sections that are approximately 4 inches in length. Pair the bases into adenine/thymine and cytosine/guanine couples. Thread the straw section pairs onto the pipe cleaner sections. Create eight of each base pair.
Twist the edges of the pipe cleaners around the fishing line in between the beads to form the rungs of the double helix ladder.
Tips and warnings
- Add extra pieces of fishing line to the top of the model for a hanging strand of DNA.
- To save money, buy plain white straws and paint them or colour with permanent markers.
- Only use non-toxic, child safe art materials. Make sure that the materials are age graded for the students.
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