I made one of these for my Biology class. It doesn't take very long and it looks pretty cool in the end. The one I made for school is colored. I've also made another one without using tools. Any way, here's what you need:
1 sheet of 8.5" by 11" paper
This can actually be done with any size of paper. This works best when the width of the sheet is around 8- 9 inches.
This could be used as a fun, cheap way to teach about DNA. Students would learn about the structure of a DNA strand and about how the four chemicals (Guanine, Adenine, Thymine, and Cytosine) combine in long complex structures to create the blueprints for what the cell makes.
NOTE: The DNA in the photos twists towards the left. As explained to me DNA actually spirals to the right. This is just a matter of which way you make your folds. Thanks to yardleydobon for pointing this out.
Step 1: Mark it down the middle
Step 2: Marking out the Sugar- Phosphate backbone.
Step 3: Marking out each Nitrogenus Base
Then make a line across each rectangle you just made. The lines on each side should point inward like a "V". As you can see, I accidentally did this wrong in the picture.
If you want to color it, this is the step to do it. Just split each rectangle in half and color each according to the Nitrogenus base.
Remember: Adenine -> Thymine and Guanine->Cytosine
To color the back bone, split each section on the sides and middle across the middle and alternate black and white.