Decided to check out pre-allo for the first time in a couple of years and thought I would chime in:
Went to Hopkins, failed calculus and chemistry first semester freshman year, failed physiology second semester freshman year, C- in intro chem lab, C- in organic chemistry I, C in organic chemistry II. I retook calculus and chemistry sophomore year and got a C in both. I never retook physiology since my school stopped offering the course...
Subsequently had a strong upward trend, but still ended up with around a 2.8 science GPA (3.1 overall). I needed to take 9 semesters to graduate though. Got a 34 on the MCAT (had to check my past posts to verify that since I couldn't remember the exact number off the top of my head).
Finished a two year master's program at Johns Hopkins School of Public Health, doing well in all my classes and worked on a basic science research project.
I was accepted to 3 schools (Drexel, MCW, EVMS), waitlisted at 2 others (Case Western, Tufts) and ended up matriculating at Drexel.
Four years later, I have been elected to AOA (national honor society), was one of a handful of people in my class to honor all my clinical rotations 3rd year, and will be starting my radiology residency at a solid program in 2012.
Honestly, if I can overcome all of that to be where I am today, a C- in one class will not break you. It might seem like the end of the world now, but its not if you work hard to make up for it.