Directions for a DNA Model Using K'nex

Parts You Will Need

• You will need just three different kinds of K'nex pieces to make the DNA model, but you will need several of each part.
  First, pick out all of the 135-degree green connectors. These parts look like a section of a snowflake. For these purposes the green connector will be called a "sugar ring," as they represent deoxyribose sugar units.
  Locate all of the short white rods and the slightly longer blue rods. The white rods will represent the phosphodiester bonds and the blue rods will represent the hydrogen-bonded base pairs in the model.

Assembling The DNA Model

• Form a helix backbone by connecting three green connectors with white rods between each connector in the outermost slots. The other connecting slots should be facing inward from the semi circle created. A third white rod should be attached to the outer slot on the right end of the model.
  Make another helix backbone using three more green connectors in the same way. This time, place four white rods on the outer slots. Two will be in between the connectors and the other two will stick out from the outer sides of the connectors.
  Attach a blue rod to the available slot adjacent to the connected white rod on each of the green connectors on the first helix backbone. Then, attach the blue rods one at a time to the same slots on the other model. You will begin to see the helix twist around itself.
  Continue the model by attaching more connectors and white rods to each side and connecting the blue rods in the same way in the middle. The model will continue to form a spiral.
  After six "sugar rings" or green connectors have been placed on each side you should notice that the sixth one and the first one you began with are oriented in the same direction. The distance between these completes one helical turn.
  Hold the model vertically to see the shape of the DNA helix. While this is obviously not an exact replica of the actual DNA helix, it will help explain how DNA is constructed.