I notice that everyone, including myself, believes that Congress is owned and operated by large corporations. Where is the real proof?

I was looking through lists of contributors to candidates and people already in government. What strikes me is the small amounts listed compared to the overall cost of the campaign. I see Louisiana candidates getting 1–5 thousand dollars for oil corporations. The biggest donation I can remember is $1.2 million to Obama from the University of California. I wonder two things, first considering the relatively small amounts would a candidate go out of their way to favor the university or corporation and secondly, how can a state funded university justify contributing to any political campaign.