Write a short note on facilitated diffusion.
GeneralClass 12AllAnswered 27 Mar 2026
Answer
Facilitated diffusion is a type of passive transport with these characteristics:
- Energy requirement: None (no ATP used)
- Direction: Along concentration gradient (high → low concentration)
- Mechanism: Requires carrier proteins (permeases) or channel proteins
- Specificity: Highly selective for specific molecules (glucose, amino acids, ions)
- Rate: Faster than simple diffusion but shows saturation kinetics
Examples:
- Glucose transport via GLUT transporters
- Ion channels (K⁺, Na⁺, Ca²⁺ channels)
Comparison: Unlike simple diffusion, facilitated diffusion can transport polar/charged molecules that cannot cross the hydrophobic lipid bilayer directly.
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