Wikipedia has a good article on Biotechnology:

http://en.wikipedia.org/wiki/Biotechnology

The types of branches are:

Red Biotechnology: relating to medical processes

White/Grey Biotechnology: relating to industrial processes

Green Biotechnology: relating to agricultural processes

Blue Biotechnology: relating to marine and aquatic applications

From what you’ve mentioned, Red Biotechnology might be the place for you.

Genetics and microbiology are large growing fields.

The biggest example of what you seem to be interested in is: how insulin is produced

Along with the genetics aspect of learning where the specific gene of what codes for insulin, and then taking that gene and incorporating it into a bacterium’s genome so it could “mass produce” insulin.

I can’t tell you for sure what schools would be the best to look at, but tyou could try http://www.petersons.com and use the links to search for schools relating to Biotechnology.

In the end, it won’t matter too much what you do in your undergraduate studies, you can study Biology….. What matters is where you get your Master’s and Ph.D….. you want to find a place where you can perform research.

I wish you the best of luck.