You need:
1 Yr of Biology (w/lab)
1 Yr of Physics (w/lab)
1 Yr of Chemistry (w/lab)
1 Yr of Organic Chemistry (w/lab)
1 Yr of English
1 Yr of Higher Math, especially Calc I, Calc II, and/or Statistics
Possibly courses in behavioral/social sciences and humanities (more school dependent)
You need those classes (listed above). Beyond that you really just need a reasonably challenging curriculum. Courses such as upper level physics, chem, and bio or biochemistry will probably help you out in med school and may help you on the MCATs, but they are not required. I have heard that individuals in writing-intensive majors tend to do better on the MCATs because they are more prepared to read and interpret the information in the MCAT’s passage style testing. Also, some upper level psychology courses may require basic biology and chemistry as prerequisites or those courses may simply be degree requirements.