If your a second year, I think you will do fine taking the courses at UCI. Start this fall with bio 93 (if you can try and take the course this summer, they are offering it on M,W,F), then take bio 94 (also offerred this summer), with lab. Take 97 & 98 and I think you will be fine. Check with the school of biological sciences to make sure. They have a listing of recomended courses for Dentistry and Medicine that they hand out to student. Also, don't forget that if you are planning to take physics at UCI, they only offer the calculus based series, so you will need to take calculus. If your not interested in doing the cal based series, look elsewhere for the physics (dental schools don't require the physics series, only the trigonometry bases ones). Take the three quarter of general chemistry (avoid Dr. Arrasasingham), and the organic chemistry series (also, three quarters). Again, taking them at another institution should consider if (a) you feel you have a greater chance of getting the grade you want (b) you are a non-science major and do not have enough time to complete the course work at your present institution (c) they offer the courses in a shorter amount of time (some places offer them in eight weeks) (d) cheaper tuition and (e) you have the time to take them with your full course load at UCI.
If you have any other question you can PM. I would be happy to answer any question, if I can.