14. Oct. 2014, 11:00 Cell membrane function

1. CELL MEMBRANE
FACTORS AFFECTING THE RATE OF
DIFFUSION

2. Summary of Membrane Transport

3. Diffusion of Nonelectrolytes
 Simple diffusion

4. Concentration Gradient (CA − CB)

5. Partition Coefficient (K)
 Solubility of a solute in oil relative to its solubility in
water


6. Diffusion Coefficient (D)
 Size of the solute molecule
 Viscosity of the medium

7. Thickness of the Membrane (ΔX)
 The thicker the cell membrane, the lower the rate of
diffusion.

8. Surface Area (A)
 The greater the surface area of membrane available,
the higher the rate of diffusion

9. Diffusion of Electrolytes
 Facilitated Diffusion
 Primary Active Transport
 Secondary Active Transport
 Cotransport
 Countertransport

11. Saturation
 Carrier proteins have a limited number of binding
sites for the solute

12. Stereospecifity
 The binding sites for solute on the transport proteins
are stereospecific

13. Competition
 Chemically related solutes can be recognized, bound,
and get transport, thereby occupying some of the
binding sites of other solutes

14. Reference:
 Costanzo Physiology 5th edition