Content is more important than how you wrote it or grammar mistakes. Being on the other side of the admissions process, I can tell you that most of the time, I skim through the application a couple minutes before the interview. I don't have time to look through it with a fine tooth comb or check every single grade you got. I'll check out your GPA and MCAT score, read your personal statement, and look at your activities so I have stuff to ask you.
GPA and MCAT is always relatively the same, and activities are usually pretty generic. So the thing that sets you apart is the interview and your personal statement. There's basically 3 things I want to know: a) Can you hang? b) Are you committed? c) Are you someone I'd like to work with and be around?
The last one is probably the most important for me. You're probably going to rotate on my service as an MS3 eventually, so there's a chance I'm going to have to work with you and be around you for some time. So if you come off as someone I'd like to work with and teach, then that probably means more than any of the other stuff on your application.