If the school doesn't specifically REQUIRE biochem, then you can get by without it. If the school specifically RECOMMENDS biochem, then you can still get by without it, but should know ahead of time that 90% of the class will have taken it, so the prof may assume you have a little background that you don't have. You can catch up with a few extra hours a week, but for some that is a disadvantage. If the school says neither, then a good chunk of the class wont have had it, and you are totally fine.
Also worth noting is that some college biochem classes are better than others, and memories for that kind of detail tend to wane, and so more than a few people who have supposedly taken biochem found themselves starting from scratch in med school anyhow. I wouldn't bother trying to teach yourself anything for med school -- I've never met anyone who tried this and felt it helped (myself included). You cannot have a sense of the pace or focus of med school until you get there, and will be wasting your time. But I suppose you could do little silly time saving things like memorizing the names and structures of the amino acids, if you have time to kill.
