Protons and neutrons are made up of up and down quarks, while other quarks contribute to a variety of baryons and mesons. Heavy quarks lead to unstable particles that typically decay quickly, though some can be relatively stable depending on interactions. The J/ψ particle is noted for its long lifetime due to decay primarily through electromagnetic and weak interactions. Additionally, the longest-lived strange particles, such as K0 and Λ baryons, have specific decay characteristics. Overall, the discussion emphasizes the complexity and instability of particles formed from different quark combinations.