Diffusion Lecture Notes

Definition and Concept of Diffusion

• Diffusion: Net movement of particles from an area of higher concentration to an area of lower concentration.
  • Particles move from crowded areas to spread-out areas.
  • Net Movement: Considers all particles as a group moving collectively.
  • Occurs due to random motion of molecules.

Characteristics of Diffusion

• Happens in both gases and liquids.
  • Example: Perfume spreading in a room; food coloring in water.
• Passive process: Does not require cellular energy, only relies on random particle movement.

Diffusion Through Cell Membranes

• Cell membranes act as barriers, allowing diffusion of certain molecules.
• Partially Permeable Membranes:
  • Allow small molecules like water, glucose, amino acids to pass.
  • Block larger molecules like proteins and starch.

Factors Affecting Rate of Diffusion

1. Concentration Gradient:
   • Greater difference in concentration between two areas.
   • Larger gradient results in higher diffusion rate.
2. Temperature:
   • Higher temperatures provide more energy to particles.
   • Results in faster particle movement and higher diffusion rates.
3. Surface Area:
   • Larger surface area allows more particles to diffuse at once.
   • Increases rate of diffusion.

Conclusion

• Understanding diffusion is crucial for comprehending molecular movement in various environments.
• Factors such as concentration gradient, temperature, and surface area significantly influence how quickly diffusion occurs.