This document discusses several cellular transport processes including diffusion, osmosis, and filtration. It explains that diffusion is the movement of particles from an area of higher concentration to lower concentration, and it is affected by factors like temperature, molecular weight, membrane permeability and surface area. Osmosis is the specific diffusion of water through a selectively permeable membrane from higher to lower water concentration areas. Filtration uses hydrostatic pressure to force water and small solutes through a membrane. The document also defines tonicity, and explains how hypotonic, hypertonic and isotonic solutions impact cell volume.

1. Filtration, Diffusion, and
Osmosis
Jo Patrick Mabelin
BS Biology 3

2. Diffusion
• Movement of particles
• Concentration of substances differ from one
point to another
• High concentration to Low concentration

4. • Factors affecting diffusion rate through a
membrane
▫ temperature - ↑ temp., ↑ motion of particles
▫ molecular weight - larger molecules move slower
▫ steepness of concentrated gradient - ↑difference, ↑
rate
▫ membrane surface area - ↑ area, ↑ rate
▫ membrane permeability - ↑ permeability, ↑ rate

5. Membrane Permeability
• Diffusion through lipid bilayer
• Diffusion through channel proteins
▫ Cells control permeability by regulating:
 Number of channel proteins
 Opening or closing gates

6. Osmosis
• Flow of water through selectively permeable
membrane
• From: Side of higher water concentration
• To: Side of lower water concentration
• Movement from lower solute concentration to
higher solute concentration

8. • Aquaporins: Channel proteins in the plasma
membrane specialized for the passage of water
• Cells increase rate of osmosis by installing more
aquaporins

9. Osmotic Pressure
• Amount of hydrostatic pressure to stop osmosis
• Osmosis Slows due to hydrostaitc pressure

11. Filtration
• Water molecules and extremely small solutes are
forced to move through a selectively permeable
membrane by a hydrostatic pressure

13. Tonicity
• ability of a solution to affect fluid volume and
pressure in a cell
• depends on concentration and permeability of
solute

14. Hypotonic Solution
• High solvent concentration
• Cells absorb water, swell, and may burst

15. Hypertonic
• High solute concentration
• Cells lose water and shrivel

16. Isotonic
• Concentration of solute and solvent are level
• No changes in cell volume and shape