It’s hard to believe 11 years have gone by since the Big Bang Theory debuted. For us at Indigo Instruments, this is particularly memorable since the new 11th season is the 10th anniversary of our DNA model(s) appearing in Sheldon & Leonard’s apartment.
The Original DNA Model
Each DNA base pair accounts for slightly less than 36 degrees of turn of the 360 degree helix. This works out to roughly 10.5 DNA base pairs which we rounded up to 11. We then decided to make it 17 base pairs or 1.5 turns and a more impressive 3 foot (~0.5m) tall model. The first one we sold went to Bell Labs in New Jersey in 2000 and we have since shipped over 300 to prestigious universities and organizations around the world.
The Big Bang Theory Model
The set designers wanted something oustanding, so they bought 2 models to stack on top of one another to produce the 6 foot tall model you see in the show. They had to build an external support structure behind it since the standard support rod was only sturdy enough for a single double helix model.
The Best Big DNA Model in the World
We’ve had requests over the years for a standalone version of the BBT model. This required modifications to ensure the major/minor groove would not be distorted over the greater height. This is not trivial since much of the chemistry of DNA takes place there and no other model represents this feature correctly (except our other teaching DNA model). Just adding a longer, stronger rod was enough to distort the model.
Further, we wanted to make it to 36 base pairs. Short peptides, 8-12 amino acids long, are important biochemically. We wanted the model to reflect this since 3 base pairs code for an amino acid. A 34 or 35 base pair version only codes for 11 and so 1 or 2 bases are “wasted”. Prof. Straus invaluable input helped us produce the 36 base pair version you see below; as technically correct as its forebear.
What Make a DNA Model Accurate?
There are 16 ways to build 2 layers of a DNA model; 64 ways to build a 3 layer model and so on. A DNA molecule has millions of base pairs and it contorts through numerous hairpin turns along its length. The 436 possible ways to build this model all have to be taken into account to make this an accurate, straight, stand up model. Read Wikipedia’s article nucleic acid double helix for more details.
The accuracy of the DNA model is best viewed by positioning our alpha helix model in the major groove. You can push it into the minor groove but it is a very tight fit which mimics the stearic hindrance seen in the real thing.