Biology courses compose part of a premed curriculum, though courses outside of the sciences as well may be required or recommended for admission to medical school. In outline, you would pursue something like the following:
General biology — 2 semesters
Biochemistry — 1 semester
General chemistry — 2 semesters, which may include an additional course in biochemistry
Organic chemistry — 2 semesters
Physics — 2 semesters
Calculus — 1 semester
Statistics — 1 semester
English/literature/writing — 2 semesters
Psychology, Sociology — 1 semester of each recommended
In the hypothetical absence of general core or distribution requirements, the above would leave over half of your remaining course selections for academic pursuits of your choosing, and would allow for study abroad, if desired.