I am a junior in high school and thinking about applying to some pretty selective schools. I am interested in majoring in molecular biology and am working on developing my "spike" in biology. I have the opportunity to work with my local college on a molecular biology project over the next year or so, but I would be helping the professor and his assistant, not necessarily conducting original research. Is this compelling for top colleges or do they really want to see you pursue an original project?
Yes, working on other people's research in science is totally okay in high school! In fact you may be surprised to learn that even in excellent colleges and graduate school, students are still working on other people's research!
This is because the way science works is that a lot of labor is needed to do research. Thus, usually only professors, PIs (primary investigators, or head of labs), and advanced grad students, really work on fully their own research.
Non-original research is standard. In fact if you came up with totally your own idea, you might not be sure that it's even good or promising. Even science competitions like Intel, usually some professor comes up with the idea.
Also, I like that you're working on research because as you may know, the whole purpose of academia is research. So colleges that are good research institutions (including famous names like Stanford, Berekeley, MIT, Harvard) have a special soft spot for people who focus on research.