A Little Knowledge

There is a joke among teachers that every science class begins with the disclaimer, “Everything we taught you last year was a lie. Now you will learn the real truth.” That is, the way to understanding is not to start, as would be logical, with the most current, complicated, and general cases (Let’s say, Quantum Chromodyamics and General Relativity in first year physics), but with simplifications and approximations. These can later, hopefully, be replaced with a more sophisticated understanding. A good example is the effort a teacher expends to explain to his or her general physics students that what they think is “centrifugal force” is really “centripetal force.” Once disabused, however, those students that go on to advanced mechanics will find out that they were right all along, but for a different reason.

You spin me right round baby, right round, in a manner depriving me of an inertial reference frame. Baby.

For an explaination: http://www.explainxkcd.com/wiki/index.php/123:_Centrifugal_Force

Another instance that came up recently is the definition of entropy. Often, it is enough to say that “disorder always increases,” unless the students in the physics class are also taking biochemistry at the same time, in which case, it is preferable to say something like, “A spontaneous reaction requires that the change in the Gibbs free energy be negative, and non-spontaneous reactions can still occur with a large enough net influx of energy.” This is not as catchy, but prevents situations like this:

Not a Bug?

As someone who studies the abnormal aggregation of proteins into amyloids, which are responsible for certain neurodegenerative conditions like Alzheimer’s disease,  I was very interested by the new idea that a certain point in the evolutionary history of proteins, the amyloid form was a feature, not a bug. That is, amyloids today are very dangerous because they are self catalyzing: a fibril acts as a template – like a seed crystal – that allows other proteins to attach. This destroys the normal function of the protein (which depends on its shape) and creates these self-reproducing, and potentially toxic, fibrils. Usually, aggregation can only get started when proteins are denatured, and lose their native shape to expose their “sticky” hydrophobic cores. However, if the amyloids once had a function as enzymes, it might be possible that they were an early evolutionary incarnation of life. In that case, rapid self-catalysis would be an evolutionary adaptive trait!