This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
The best method to differentiate proteins is by 
Select and explain. 
A. Gel chromatography, B. Affinity chromatography, C. Ion exchange electrophoresis, D. None of the above
A: Gel chromatography
Answer: A: Gel chromatography 
Explanation: Gel filtation chromatograpy is also known as the molecular sieving Hydrophilic cross linked gels like acylamide(sepacryl),agarose(sepharose) and dextran(sephadex)used for the seperation of molecules based on their size. Sephadex is widely used and the range of seperation is based on porous size. The gel paicles are in porous in nature. The small paicles enter the gel paicles, then come out,re-enter into the another paicleBut the large picles cannot enter the pores and sidrack the gel paicles; so they move rapidly. In sho, larger molecules will come out first, while smaller molecules are retained in the column. The gel filtration techinque is used for (a) seperation of protein molecules;(b) purification of proteins; and (c) molecular weight determination. REFERNCE : DM VASUDEVAN TEXT BOOK, SEVENTH EDITION ; PAGE NO:450