In biology, comparing counts of molecules coming from control and
experimental samples is a very tricky business.
Why? Change in a biological system involves many variables
that together give a single result - the one we typically publish in
our papers. Unfortunately, there's more to counting molecules
than we might expect - much more.
In this example, we consider how molecules change in a simple
biological setting. The purpose of the exercise is to let us
change each of four variables - one at a time - and see what
happens. With a little practice, for example, we can get results showing
increases or decreases in the molecular counts - even when the
actual number of molecules in the control and experimental stays
exactly the same.
What does this mean? Biology 1 - biologist 0.
The point of the exercise is illustrate that detecting a change
in the number of molecules is one thing, whereas explaining why the
molecules change is quite another. This point becomes
perfectly clear by running the same experiment with and without