Q28. The stationary phase used in gel filtration chromatography is composed of
____
(A) Blue dextran
(B) Carboxymethyl (CM) cellulose
(C) Diethylaminoethyl (DEAE) cellulose
(D) Sepharose
Gel Filtration Chromatography Stationary Phase: CSIR NET Q28 Solved
The correct answer to Q28 is (D) Sepharose, as it serves as a key stationary phase in gel filtration chromatography due to its porous agarose beads ideal for size-based separations.
Option Analysis
Gel filtration, or size exclusion chromatography, uses porous beads as the stationary phase where larger molecules elute first by exclusion from pores, while smaller ones enter and elute later.
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(A) Blue dextran: This acts as a calibration standard for void volume, not the stationary phase itself.
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(B) Carboxymethyl (CM) cellulose: Used in cation-exchange chromatography for charge-based separation, not size exclusion.
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(C) Diethylaminoethyl (DEAE) cellulose: Employed in anion-exchange chromatography due to its positive charges, unsuitable for gel filtration.
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(D) Sepharose: Composed of cross-linked agarose beads with defined pores, making it the standard stationary phase for protein and macromolecule purification.
Gel filtration chromatography, a cornerstone in stationary phase gel filtration chromatography, separates biomolecules by size using porous matrices like Sepharose. This technique proves essential for CSIR NET Life Sciences aspirants tackling purification methods in molecular biology and biotechnology.
Principle and Mechanism
The stationary phase gel filtration chromatography relies on a porous bead matrix equilibrated with buffer; large molecules bypass pores and elute quickly, while small ones diffuse inside for delayed elution. Common matrices include agarose (Sepharose), dextran (Sephadex), and polyacrylamide, selected by fractionation range for proteins or nucleic acids.
Why Sepharose Excels
Sepharose’s cross-linked agarose offers high porosity (e.g., Sepharose 4B for 60-20,000 kDa), chemical stability, and minimal nonspecific binding, outperforming rigid alternatives in biotech labs. It supports high flow rates and scalability from analytical to industrial purification.
Applications in Life Sciences
This method purifies enzymes, desalts samples, and determines molecular weights, aiding genetic engineering and CSIR NET-relevant topics like protein folding. For competitive exams, note its distinction from ion-exchange phases like CM or DEAE cellulose.
