definately dont worry about it,youll do fine. its really just about how much time you spend studying, and what level of knowledge you are happy with, i.e. its pass/fail and youll probably pass regardless. granted, people who are there are biochem majors will have an easy time with that course, and maybe you'll need to study more than them, but whats the point of taking something twice? you probably took advantage of undergrad and took some great classes that they couldnt take. there are many people at Sinai every year with less than the minimum(i.e. only one year bio, one year chem, thats it, essentially no orgo, no physics, no math, no MCATs etc etc), and they are doing as well, and/or better than others(special program at sinai etc).