I think that schools do like to see a lot of them completed (You only have 1 year after you apply, if you apply in summer, to take classes anyway). You would need to take 1 year bio, 1 year chem, & 1 year ochem for the DAT so those should be done. But upper div requirements like biochem can probably wait. Be careful of the deadlines for some of the schools, some don't let you take the pre reqs during summer school before you matriculate or you don't have time for summer school cause some d schools start in july. IMO physics is good to take the year you apply because it doesn't come out on the DAT and stuff.