Problem...please help!

Ah very difficult! Definitely get both. I have certainly seen schools that require two letters from profs you've actually had in lecture courses, but not all schools require that.

 

I'd say get both, but if you have to choose, then pick the prof that knows you the best (and can therefore write the best LOR). At my top-choice school, the LOR requirements are pretty flexible... i.e., you're supposed to have a letter from a non-science prof, but I don't have a non-science prof, so I'm substituing it with an LOR from an EC advisor.

Talk to the admissions office-- they can tell you if you absolutely have to have been a student in the prof's class or if you can use an LOR from the prof you TA-ed for.

 

Some medical schools will specifically require letters of recommendation from professors that can comment on your academic work. You can ask many different people to write letters for you and then pick and choose which letters to send to which medical schools (provided that your undergraduate institution does not have a pre-medical committee).

 

get both. here's why--
I've heard that Ad Coms like to get LORs from profs that have actually taught you b/c they can compare you to the hundreds of other premeds they've taught, and show them that you're "superior." Sorta like saying, "I've taught X amount of kids, with Y in each class, adn I can vouch that <your name> stands out as a brilliant student with thought provoking questions and . . blah blah blah." That's what you can expect your organic chem prof to say, among other things (which is good b/c Ad Coms like to see exactly that).

Your Bio profs that you've TA'ed for can emphasize that by saying that you've actually worked for them, and speak of your intellect, communication skills, and ability to help other students when needed.
You see how these two letters (both from faculty) can sound different? Make sure your Bio prof addresses qualities that your Ogro prof can not address--communication skills, ability to go out of your way and help students etc.

Hope it makes sense. Good luck
Tweetie