How worried should I be about my grades?

Hello forum,
I am a senior and throughout high school I have taken all available honors and AP’s and received a mix of A’s and B’s. However, I really screwed the pooch on my semester 1 finals this year and as a result, I will have a C+ and a C- this semester (the rest are mostly B’s). I have already been accepted the University of Minnesota, Twin Cities and am wondering if it would be likely for them to rescind my acceptance when they receive my final transcripts. I am also wondering about schools that I thought I would otherwise have been a viable candidate for, such as: University of Washington, UC Santa Barbara, Boston University, Tulane and others. How much of a disservice have I done myself? I feel my resume is otherwise decent (you can see most of it here http://talk.collegeconfidential.com/college-search-selection/1823678-where-do-i-stand.html#latest) but I have heard many stories about students who have been rejected because they did poorly senior year.

I apologize if this a question you have been getting excessively around this time of the year. I just wanted to make sure I could get an answer specific to my exact situation.