Components required for iPhone 4 to sync?

Hi there,

I have have two broken iPhone 4's . Taken apart. And separated into their individual components. And between them, I'd like to make one sync with my iTunes. Just one last time!

What are the minimim required components that must be attached and in place inside the iPhone 4, in order for the phone to turn on and for iTunes to recognize it?

I'm betting the camera isn't needed? Nor the vibration generator? And probably not even the battery?

Thanks ahead of time!
- ShiloCM