These are some great biology videos from Harvard University.
Biovisions - Inner Life of a Cell
https://www.youtube.com/watch?v=wJyUtbn0O5Y
Biovisions - Powering the Cell: Mitochondria
https://www.youtube.com/watch?v=RrS2uROUjK4
and a lot more available at:
http://multimedia.mcb.harvard.edu/media.html
The Youtube versions are better for a projector screen than the ones you can get on the Harvard site. (Larger and clearer).
Inner Life of a Cell is a great way to introduce cell parts, either for juniors and seniors.
