This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
In SDS-PAGE (Sodium Dobecyl Sulfate-polyacrelamide Gel Electrophoresis) proteins are separated on basis of 
Select and explain. 
A. Mass, B. Charge, C. Density, D. Molecular weight
D: Molecular weight
Answer: D: Molecular weight 
Explanation: SDS PAGE electrophoresis is a variant of PAGE. separation of molecules will depend mainly on their molecular size. Hence it is mainly used for molecular weight determination as well as for assessing purity of proteins.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 447