This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which of the following seperates proteins solely on the basis of it's molecular size? 
Select and explain. 
A. Iso-electric focussing, B. Gel filtration chromatography, C. Chromatography on a carboxymethyl (CM) cellulose column, D. Chromatography on a diethylaminoethyl (DEAE) cellulose column
B: Gel filtration chromatography
Answer: B: Gel filtration chromatography 
Explanation: Hydrophilic cross linked gels such as acrylamide, agarose and dextran are used for separation of molecules based on their size. Dextran ( sephadex) is widely used and the range of separation is based on pore size designated by the symbol G10 to G200. In this technique large molecules will come out of the column first and large molecules are retained in the column. This technique is used for separation of protein molecules, purification of proteins and molecular weight determination. Ref: Vasudevan Biochemistry, 3rd Edition, Page 56 ; Biotechnology 101 By Brian Shmaefsky, Page 89 ; Comprehensive Biotechnology XI By Dr. A. Jayakumaran Nair, Page 254