And deleonrg- in this scenario are you referring to chem bringing down your MCAT or gpa? If MCAT, from my experience, there aren't enough questions on one specific subject (ie chem) to truly tank a score. It's a very diverse test, with the exception of the VR section, which you either get or you don't. As for GPA, short of being a chem major, not doing great in chem courses isn't going to tank an overall science gpa, as you still have to have Cs (2.0) to pass.
Cali- not sure where you've heard otherwise, but I would question it. Yes, the "total package" is what they're looking for, however it seems as though many more with below average gpas are getting in with above average mcats than the other way round. I'd even wager that adcoms weigh the VR section of the MCAT a little more heavily, as it tests your ability to read critically and discern useful information from useless information, in a stressful test environment, as opposed to typical PS or BS type questions which are more "cut and dry" if you will.