In a gel electrophoresis setup, proteins are loaded at the top; under electrical current, smaller things move down faster and larger things tend to remain near the top.

“Yeah. So, um, on the right here, we have, uh, what's known as a western blot. If you want to... Or sorry, uh, a gel. If you want to think about this as like, um, a physical object, it's basically just a sheet of gelatin.”

“A, um, scientist loads protein at the top, so at the, um, like very top of the Y-axis, and then the protein just kind of floats down.”

“Small things float down quicker, um, larger things sort of hang at the top when you apply electrical current. So in this case, the scientist has something very complicated.”