Technically, 2 semesters of Ochem, 2 semesters of bio (pref. cellular/molecular and genetics), but physiology and biochemistry are also helpful. 2 Semesters of Physics.
I took the MCAT after 1 semester of physics, cellular bio, and g chem. however I studied the rest of the material on my own. I got a 31 S, but I know if I had taken it a year later I would have gotten mid thirties probably...
Personally I think 2 semesters G chem, 1 semester o chem (you dont really need second semester), cellular/molecular bio, genetics (!!!!), 2 semesters physics and if you can take biochem, it would prolly help.