Biochemistry Online: An Approach Based on Chemical Logic

Biochemistry Online




Last Update:  04/08/16

Learning Goals/Objectives for Chapter 6A:  After class and this reading, students will be able to

  • define flux (J) of solute (A) across a membrane;
  • write mathematical relationship that show how flux J depends on the concentration gradient of solute across the membrane (dA/dx) and also on the difference of solute concentration across the membrane (ΔA) for passive diffusion;
  • differentiate between passive diffusion, facilitated diffusion mediated by a receptor transporter, and active transport
  • write chemical equations which show the physical steps in the process of passive and facilitated diffusion
  • derive a mathematical equation and graphs which shows the dependencies of flux J as a function of Aout and AR for facilitated diffusion assuming rapid equilibrium binding of ;
  • differentiate between carrier proteins, permeases or transport proteins on one hand and channels on the other;


A6.  Links and References

  1. Science 322: 1655 (2008) 
  2. Huang, Y. et al. Structure and mechanism of the Glycerol-3-Phosphate Transporter from E. Coli. Scinec. 301, pg 616-620 (2003) 
  3. Abramson, J. et al. Structure and mechanism of the Lactose Permase of E. Coli. Science. 301, pg 610-615 (2003)
  4. Locher, K. et al. Breaching the Barrier (review of transport proteins LacY and GlpT. Science. 301, pg 603 (2003)
  5. Alper, J. Breaching the membrane (new ways to move drugs through membranes).  Science.  296. pg 838 (2002)
  6. Murata et al. Structural Determinants of Water Permeation through Aquaporin I.  Nature. 407, pg 599 (2000)
  7. Fu et. al. Structure of a glycerol-conducting channel and the basis for its selectivity. Science 290. pg 481 (2000)
  8. Sui et al. Structural basis of water-specific transport through the AQP1 water channel.  Nature. 414. pg 872 (2001)
  9. deGroot and Grubmuller. Water Permeation Across Biological Membranes:  Mechanism and Dynamics of Aquaporin-1 and GlpF.  Science.  294. pg 2304, 2353 (2001)
  10. Aqivst and Luzhkov. Ion permeation mechanism of the potassium channel. (dynamics results). Nature. 404 pg 881 (2000)


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