Hi! I think the answer to alot of questions are "It depends on the school". Most schools look at overall and pre-req GPA, some look at just overall or just pre-req. If microbiology is not a pre-req class for the program you are interested in, I wouldn't stress too much over it. I def. have a few C's in other courses, so I know that it sucks and C's don't help in the cause of GPA... Stay positive and focus on the main requirments to get into a program. This is just my thought. Good luck!