Just be careful not to apply to a med school that has a stated requirement of a C+ or better in the prerequisites. Even with those, if they allow a substitution, you might be fine if you got a good grade in Biochem.
A high grade in Biochem would redeem a C in OChem II, for most schools. But there are some schools that will require OChem II and not accept a C grade no matter what excellent Chem grades follow. Just be sure to read websites carefully and avoid those when you apply.