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Terms in this set (45)

A type of PASSIVE protein-mediated transport
1. A kind of carrier - mediated transport - requires a CARRIER PROTEIN (transport protein)
2. A molecule transported via carrier-mediated diffusion will cross membrane FASTER than a molecule of similar molecular weight and lipid solubility which crosses via simple diffusion
3. Speed of diffusion depends on concentration gradient but MAXIMUM rate (Vmax ) is limited by number of carrier proteins and/or speed of binding/ release from carrier.
4. The maximum velocity of diffusion (Vmax) is also called the transport maximum Tmax or Tm)
5. Carrier protein shows chemical specificity and stereospecificity
6. Structurally related molecules may COMPETE for transport. [This is ANALOGOUS to COMPETITIVE INHIBITION of an enzyme.]
7. NONCOMPETITIVE INHIBITION is possible when substance I interferes with the transport of substance A even though substance I is not transported by the carrier.
8. *CANNOT* transport uncharged substances against concentration gradients. CANNOTCANNOTOT* transport uncharged substances against concentration gradients. *CANNOT* transport ions against electrochemical potential gradients.
9. GLUCOSE enters most cells via carrier-mediated diffusion. Other monosaccharides (e.g. galactose) compete for the same carrier. One of the actions of INSULIN is to INCREASE the number of glucose transport proteins in the cell membrane of SKELETAL MUSCLE CELLS AND ADIPOCYTES.
10. Carrier-mediated diffusion is a TYPE of FACILITATED DIFFUSION. Terminology can differ among different textbooks but most texts call carrier-mediated diffusion facilitated diffusion.