The reason the elevator pitch is such a highly stressed aspect of start-up marketing is because investors have notoriously low attention spans from listening to pitches all day, every day.
A solid pitch that is concise at least lets them decide if they have any interest at all before going into the deeper details.
The Human Genome project can be explained in less than 120 words. I have a gut-feeling that that you aren't talking about decoding DNA.
Think about the following questions:
What are you going to build?
Why should we believe you are willing and able to build it?
Everything else is fluff...so, for every sentence you write, think, "Does this answer one of those two questions?" If not, cut it. That's pretty much what all of the questions on the application are about--they just want to hear it from multiple angles.
make it easy to parse what you're doing and why it's valuable. part of that is being focused, and brief.
The verbose application/business plan can wait until the VC is actually interested in your company and requests a more detailed plan. (not to say that you should wait until the last minute to draft your BP though)