41.
In gel filtration chromatography, separation of proteins are based on their

• (A) Size and net charge
• (B) Size and shape
• (C) Size and specific affinity
• (D) Shape and net charge

  Gel filtration chromatography separates proteins based on their hydrodynamic volume, which primarily reflects size and shape, not charge or affinity.

  Option Analysis

  • A. Size and net charge: Incorrect. While size matters, net charge is irrelevant in gel filtration as the inert porous matrix has no charged interactions—charge governs ion-exchange chromatography instead.​

  • B. Size and shape: Correct. Proteins separate by hydrodynamic volume: larger/less symmetric proteins elute first (excluded from pores), while smaller/more compact ones enter pores and elute later.

  • C. Size and specific affinity: Incorrect. Affinity is for biospecific binding (e.g., ligand-protein); gel filtration uses no ligands, relying purely on physical exclusion.​

  • D. Shape and net charge: Incorrect. Shape influences hydrodynamic radius alongside size, but charge plays no role in this non-ionic technique.​

  Correct Answer: B

  Introduction to Gel Filtration Chromatography Separation

  In gel filtration chromatography, separation of proteins is a core concept for GATE Life Sciences prep, distinguishing it from charge- or affinity-based methods. Proteins navigate porous beads differently by their hydrodynamic volume—directly tied to size and shape—for effective purification and desalting.

  Principles of Protein Separation in Gel Filtration

  The technique uses inert, porous matrices (e.g., Sephadex) where large proteins pass quickly through voids, while small ones diffuse into pores, delaying elution. No chemical interactions occur; separation hinges on molecular dimensions under native conditions.

  Comparison of Separation Factors

  Option	Factors	Correct for Gel Filtration?
  A. Size and net charge	Hydrodynamic + ionic	No; charge irrelevant ​
  B. Size and shape	Hydrodynamic volume	Yes; core mechanism
  C. Size and specific affinity	Volume + biospecific	No; no ligands used ​
  D. Shape and net charge	Asymmetry + ionic	No; excludes charge ​

  Size and shape dominate, ideal for oligomer analysis or buffer exchange.​