Diffusion Overview

Definition of Diffusion

• Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
• Particles move from an area where they are bunched up (high concentration) to where they are more spread out (low concentration).
• "Net movement" refers to the overall movement of particles as a group.

Random Motion

• Molecules move randomly if left alone.
• Over time, they spread out to become evenly distributed in the available space.
• Diffusion can occur in gases and liquids.
  • Example: perfume diffusing in a room.
  • Example: food coloring diffusing in water.

Diffusion Through Cell Membranes

• Cell membranes are partially permeable, allowing only certain molecules to pass through.
• Small molecules like water, glucose, and amino acids can diffuse through.
• Larger molecules like proteins and starch cannot pass due to their size.
• Diffusion is a passive process, requiring no energy from the cell.

Factors Affecting the Rate of Diffusion

Concentration Gradient

• The difference in concentration between two places.
• Larger concentration gradient results in a higher rate of diffusion.

Temperature

• Higher temperatures provide more energy to particles.
• Particles move faster at higher temperatures, increasing the rate of diffusion.

Surface Area

• Larger surface area allows for more particles to diffuse at once.
• Higher rate of diffusion occurs across a larger surface area.

Conclusion

• Understanding diffusion is crucial for comprehending various biological processes.
• Key factors include concentration gradient, temperature, and surface area.
• Diffusion is an essential concept in biology, particularly in understanding cell function.