Diffusion

• What is diffusion?

  Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration
• Why is diffusion a passive process?

  It doesn't require energy
• What is simple diffusion?

  Simple diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration.
• What type of molecules can be transported by simple diffusion?

  Small, non-polar molecules
• Why do small molecules undergo simple diffusion?

  They can pass through the spaces in the phospholipids
• Why do non-polar molecules diffuse via simple diffusion?

  They can dissolve in the hydrophobic core of the cell membrane
• What type of molecules need facilitated diffusion?

  Large or polar molecules.
• What proteins are involved in facilitated diffusion?

  Channel & carrier
• How do carrier proteins work?

  Large molecule attaches to carrier protein

  Protein changes shape

  Carrier protein releases molecule on other side of membrane
• How do channel proteins work?

  They acts as pores in the membrane
• How does increasing temperature affect rate of diffusion?

  Particles have more kinetic energy, so diffuse faster
• How does concentration gradient affect diffusion?

  Steeper concentration gradient = faster diffusion
• How does membrane thickness affect rate of diffusion?

  Thinner membrane = shorter distance to travel = faster diffusion
• How does surface area affect rate of diffusion?

  Large surface area = more particles can cross membrane = faster diffusion
• How does increasing the number of channel & carrier proteins affect rate of diffusion?

  It increases it