If you're not taking many other courses and don't have many extracurriculars, then you can try. However, unless you're great at rotating studying very efficiently, you might become overwhelmed. First semester biochem isn't too bad; cell bio probably isn't too bad; orgo 2 is going to require a lot of practice, though. If you go ahead with this plan, just be prepared to study often and a lot for all of your classes. Combined, they can make for an onslaught of information.