<prompt> Proton consists of:2 up quarks 1 down quarks2 up quarks 2 down quarks1 up quarks 2 down quarks1 up quarks 1 down quarks  <response>: Protons are spin-12 fermions and are composed of three valence quarks, making them baryons a sub-type of hadrons. The two up quarks and one down quark of a proton are held together by the strong force, mediated by gluons. 