Just to give you an idea right away, the general prerequisites are:
8 SH (12 QH) Biology
8 SH (12 QH) Inorganic Chemistry
8 SH (12 QH) Organic Chemistry
8 SH (12 QH) Physics
Then of course there's the English requirement (usually varies between 6 and 12 SH) and the math requirement (through Calculus II).
I've found that some of the schools require 12 SH of biology, and then some schools require that you take 6 SH or more of a behavioral science, such as psychology, anthropology, sociology, etc.
So that's the general idea, but definitely look at those websites posted by the above. They are very helpful.