I've never read YA, but when I was 16 or so, I began getting really really into White Wolf's Werewolf game, and the thing about that is, that it's really intense, with loads of detail, and we ate it up! I would say that more important than dumbing it down is making it fun, realistic, and intense, because young people respond to those strong emotions. I'm not sure whether the science you are going into is hard to understand, but there have been loads of great suggestions on this thread. If you were interested in the science, I say write it in how you like it and then ask some young people to read it and see if it is at their level or whether it bores them. Kids are pretty smart, and they're probably smarter now than when I was young (with computers and smart phones within reach at all times... )