Very nice... I especially liked the basics on what quarks are and how we go from protons to neutrons.

One question that lingers is that protons carry a positive charge and neutrons have, well a "neutral" charge. As I understand, the neutrinos do not carry a positive charge (or they'd be easier to detect, right?).

So what happens to the positive charge from the proton? Or is the charge simply a property of the up/down quark combination and does not exist in and of itself?