American Masters

Using physical and chemical clues scientists have been able to figure out how the DNA molecule looks in detail. Well, gee, what kind of stuff is DNA? It's who you are. That very core of your being. It's in your DNA is in your genes. If you're talking about the molecule of life it has to be able to do an incredible number of things right it has to exist in every cell, it has to have enough diversity that from that information you can create an entire organism and it also has to be able to replicate itself so understanding the structure of the DNA molecule is really key to thinking about how all of these properties can exist in a single molecule. DNA is often called a double helix. It's two strands... kind of like a pair of spiral staircases... like a twisting ladder... those are DNA's backbones. There's no information per se in the background. What those backbones are supporting in between them... the rungs of the ladder... that's what makes each of us genetically distinct. The whole of nature's instructions are printed in these four chemical letters. The rungs are called bases which are these little compounds.

There are four bases

Adenine, Cytosine, Guanine, and Thymine. A, C, G, AND T. And they they bond together with hydrogen bonds. A always pairs with T, C always pairs with G. We have four different puzzle pieces that you can arrange in any number of ways. If you change the sequence of bases that can change the organism itself. If you take those two strands and you pull them apart you can rebuild a new second strand on each one of those and you will have two identical copies of the original DNA molecule. That tells you how hereditary information is passed down to the next generation. That's the central insight of the double helix.