Final answer:
The migration rate of proteins on cellulose acetate is primarily affected by their charge, which is the key factor that determines how fast and in which direction they will move during electrophoresis.
Step-by-step explanation:
The migration rate of proteins on cellulose acetate is primarily the result of the charge of the proteins. Electrophoresis is a process where plasma is made alkaline and at a pH where all plasma proteins will have a negative charge. When an electric current is applied, proteins migrate towards the anode, but at different rates depending on their charge intensity. Although factors like molecular weight and shape also play a role, it is the charge that predominantly affects the migration rate in this context.