Veterinary Biochemistry- ICAR JRF/SRF 2024

• Electrolyte Distribution in Body Fluids:
• Intracellular Fluid (ICF): Potassium ($\text{K}^+$) is the predominant intracellular cation, maintaining a normal concentration of approximately $140\text{--}150\text{ mmol/L}$ (or $\text{mEq/L}$).
• Extracellular Fluid (ECF): The $\text{K}^+$ concentration in plasma is much lower, tightly maintained at $3.5\text{--}5.0\text{ mmol/L}$, whereas sodium ($\text{Na}^+$) is the principal extracellular cation ($135\text{--}145\text{ mmol/L}$).
• Maintenance: This steep electrochemical gradient across animal cell membranes is established and sustained by the plasma membrane $\text{Na}^+/\text{K}^+$-ATPase pump.

Correct option: (1) 140 m mol/L

• Sensitivity of Protein Stains in Polyacrylamide Gels (PAGE):
• Silver Stain: The most sensitive non-radioactive colorimetric stain, capable of detecting as little as $0.1\text{--}1\text{ ng}$ of protein per band. It relies on the binding of silver ions ($\text{Ag}^+$) to protein functional groups followed by chemical reduction to metallic silver ($\text{Ag}^0$).
• Coomassie Brilliant Blue (R-250 / G-250): Standard sensitivity, detecting approximately $10\text{--}50\text{ ng}$ of protein.
• Amido Black: Lower sensitivity, detecting approximately $50\text{--}100\text{ ng}$ of protein.

Correct option: (4) Silver stain

• Phase I Xenobiotic Metabolism: Catalyzed by the microsomal Cytochrome P450 monooxygenase system in the smooth endoplasmic reticulum:

• Reducing Equivalents: The required electrons/reducing power are supplied by NADPH, which transfers electrons to cytochrome P450 via the flavoprotein NADPH-cytochrome P450 reductase (containing FAD and FMN).
• Source of NADPH: Mainly generated via the pentose phosphate pathway (HMP shunt).

Correct option: (1) NADPH