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outline 5
Comparative Physiology- Renner Lecture 5
| Term | Definition |
|---|---|
| what is required for passive transport? | no energy. just a concentration gradient and/or chemical gradient across cell membrane as a driving force |
| what is rate of diffusion for lipid soluble substances dependent on? | 1. number of H-bonds broken for water 2. substance lipid solubility |
| how does diffusion through aqueous channels occur? | K+ (or ion) impinges on channel wall transporting across a resistance. levels off eventually |
| what are passive transport routes? | 1. diffusion of lipid soluble substances 2. diffusion through aqueous channels 3. passive carrier-mediated transport |
| What is the criteria for passive-carrier mediated transport? | 1.saturable, peaks then goes down 2. selective. presences of similar molecules won't affect the rate of transfer for a given carrier. 3. inhibited by competitive inhibitors, molecules similar to transported ones. 4. direct energy use not required |
| what are mechanisms for carrier mediated transport? | 1. uniport 2. symport 3. antiport |
| what are Uniporters? | Carriers that simply transport a molecule from one side of the membrane to the other |
| what kind of transporter is the glucose transporter found on RBC membrane? | Uniporter that has an active site that binds glucose, brings in inside the cell and changes its conformation |
| What is a symport? | a coupled transporter that uses electrical and/or chemical gradient to drive transport of another substance in the same direction. However, the transport s energetically unfavorable. |
| Give an example of a symport and explain how it works | Transport of amino acids from invertebrate gut across intestinal mucosal cells to blood. Na+ has chem/elec driving force, X against conc gradient. Na+ binds to X, Na+ overcomes small force of X transporting it out the cell. Energy expense= Na+/K+ pump |
| What is an Antiport? | couples transporter that transports substances in the opposite direction. Exchange involves ions having the same charge across opposite sides of the membrane. |
| give an example of an antiport | Bicarbonate-chlorine transporter. Bicarbonate and chlorine both have -1 charge 1 bicarbonate in, 1 chlorine ion out |
| what is the importance of an antiport ? | maintains electrical balance across membrane because both substances have the same charge |
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