I understand why everyone says that you should take your classes at a 4 year university. I also understand that schools look better at your application when you take most/all your pre-reqs at a 4 year university.
However, these are different times and it is shameful when classes at cc are looked down upon or not thought to be as hard. I went to cc and because of the area I live in I have had a few professors who taught classes at both cc and Stanford! My English and econ teacher taught my class at cc and Stanford...same syllabus! Also, in all my science classes I have had 100% PhD professors...many students in my ochem class are taking it as a refresher or re-taking it altogether. All these have come from the UC's....UC Davis, Berkeley, LA, Irvine...you name it...and all have said it is harder in our cc class than the ochem class they took at their UC. Also, we are taught by our professors (I would like to reiterate all PhD's) and not TA's. The cc professors, especially in science, do not have lower standards than those at 4 year universities. Yes, some classes are easier....BUT those are the remedial classes, not any of the classes that are pre-reqs. Also, in my area the only pre-req class not offered at cc is biochemistry. However, there are several cc in the LA area that do offer biochemistry. Ochem is considered an upper division course and it is offered at all the cc's.
To answer the original post, take whatever classes you can while at UC Irvine as far as pre-reqs. If you will be done with your major before you finish all the pre-reqs save your money and go to a cc. You probably live near one of the cc's that even offer biochemistry.
It is expensive to get an education, and if you can take the same class at a cc for a fraction of the price at a 4 year university....why not? You are smarter if you do. Unfortunately the classes taken at cc are looked down upon. I feel a lot of the people who say cc class pre-reqs do not look as good have not attended cc. I may be saying this because I live in California...and there are some top notch cc's in this area. Society really needs to not look down so much at cc. The idea of people looking down on cc reminds of the whole debate with public vs. private high school. It all depends on the individual. The same individual can sink or swim in either environment.