Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated...
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![Page 1: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/1.jpg)
Some Transport Types
• Simple diffusion (Down a chemical or electrical potential gradient)
• Facilitated diffusion (Down a chemical or electrical potential gradient)
• Primary active transport (Against a chemical or electrical potential gradient)
• Secondary active transport (Against a chemical or electrical potential gradient)
• Ion channel (Down a chemical or electrical potential gradient, may be gated)
• Ionophore mediated transport (Down a chemical or electrical potential gradient)
![Page 2: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/2.jpg)
Classes of Transport
• Uniport
• Cotransport– Symport– Antiport
![Page 3: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/3.jpg)
Fig 12-43
![Page 4: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/4.jpg)
Aquaporin
• Six helices per chain
• Four chains form a pore– Single file, 5 108 molecules per second
• Cf. 4 107 s-1 turnover number for catalase
– Water “flows” in the direction of the osmotic gradient
![Page 5: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/5.jpg)
Glucose Transporter
• 12 transmembrane helices per chain
• 5 chains form a pore– GluT1 (erythrocytes) Kt ~ 1.5 mM
– GluT2 (liver and other) Kt ~ 66 mM
– GluT4 (myocytes and adipocytes) insulin stimulates installation in membrane
![Page 6: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/6.jpg)
Figure 12-27
![Page 7: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/7.jpg)
Box 12-2 figure 1
![Page 8: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/8.jpg)
Chloride-Bicarbonate Exchanger
• In respiring tissues– CO2 in by simple diffusion, then HCO3
- out, Cl- in
• In lungs– HCO3
- in, made into CO2, Cl- out
• Antiport
![Page 9: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/9.jpg)
Fig 12-28
![Page 10: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/10.jpg)
Active Transport
• The hydrolysis of ATP or other energy-releasing reaction is required.ATP + H2O ADP + Pi
• The energy is required to move against a chemical (concentration) gradient or an electrical (voltage) gradient (the latter usually means both)
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Fig 12-30
![Page 12: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/12.jpg)
ATPases
• P-type– Cation transporters
• V-type– Proton transporters (acidifiers)
• F-type– Proton transporters in bacteria, mitochondria,
and chloroplasts (also ATP synthases)
• Multidrug transporter (tumor cells)
![Page 13: Some Transport Types Simple diffusion (Down a chemical or electrical potential gradient) Facilitated diffusion (Down a chemical or electrical potential.](https://reader035.fdocuments.us/reader035/viewer/2022062511/5513f4f755034679748b5df2/html5/thumbnails/13.jpg)
Na+K+ ATPase• P-type
• 3 Na+ for every 2 K+ in
• Fig 12-33
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Other P-type systems• Plasma membrane Ca+ pump
– SERCA pump
• Cotransport systems
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Fig 12-36
Cotransporter can pump to a 30,000 to 1 glucose level!
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Other Ion Channels
• Ligand and Voltage gated– Na+, K+, and Ca++
– On-off operations• Neurons, etc.
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Ionophores (Fig 12-37)