You've Now Heard of a Western Blot

Biologists are interested in proteins, because they do so much. In fact, if there's anything to be done on a molecular level, it's mostly proteins that do it. To most people, protein is something you get in meat; something athletes are interested in; the basis of some diets. It's clearly a category of things, but they are all roughly equivalent. In biology, this couldn't be further from the truth. There are tens, maybe hundreds of thousands of different proteins, depending on your definition. People dedicate their whole lives to studying a single protein. Genes are much more famous though. They are passed from one generation to the next and everyone knows about the double helix. Genes are the grist to evolution's mill.

Well, a protein is to a gene as a running program is to the program's code. Most analogies fall down somewhere, and this one falls down all over the place. The point is that a protein is directly reliant on a gene for its existence, but once its out there, it can do all sorts of wonderful things. For every gene there is a protein, and often more than one. Genes tend to sit in cellular nuclei, while their protein minions do their bidding all over the place. Genes are largely stable, while proteins come in and out of existence all the time, depending on the needs of a cell.

Western Blotting is a really common technique in biology. The aim is to find out whether certain proteins are expressed and to what degree, and also whether certain treatments change their expression. For such a central component of a life scientist's toolkit, the visual results are abjectly boring. They are ubiquitous though, and if you pick up a journal article from a science journal (which is extremely unlikely for the average person) you may encounter one. The input to a Western Blot is any kind of biological sample containing protein, and the output is these bands. A Southern Blot detects DNA, and was named after Mr Southern (true story). The theme was extended with Northern Blots (RNA), Western Blots and the very rare Eastern blot, which i'm told detects lipids. These substances account for the contents of every single organism, save for precious carbohydrates and other organic compounds like cholesterol, and minerals.

I could write for a long time about Western Blotting, but that would be bad. The main thing you need to know is that the dark bands represent proteins, and these dark bands can be there, or not be there, they can be thick or thin, high or low. All these things tell you about the nature of your protein sample. To the trained eye, much information can be gleaned from a blot. As with all techniques in science, interpretation is everything, and there are many assumptions and variables involved.