2. Outline for Today Introduction Passive Processes Simple diffusion Osmosis Filtration Facilitated diffusion Active Transport Introduction Solute pumping Na+/K+ ATPase pump Bulk transport Endocytosis Exocytosis
3. Active Transport Cells must use energy since the movement is non-favorable ATP ADP + Pi Non-favorable means it goes against the concentration gradient ATP Pi Pi Energy Energy ADP Introduction
5. Na+/K+ ATPase pump Movement of materials against the gradient Fig. 3.19 Solute Pumping
6. Na+/K+ ATPase pump Transmembrane Pump moves both Na+ and K+ Antiport Enzyme catalyzes the degradation of ATP This pump never stops Can burn energy while asleep Fig. 3.19 Solute Pumping
7. Na+/K+ ATPase pump It maintains a high extracellur and low intracellular [Na+] by moving Na+ (blue) outside It maintains a low extracellur and high intracellular [K+] by moving K+ (yellow) inside Mnemonic Fig. 3.19 Solute Pumping
8. Mnemonic Kout Nain Naout Solute Pumping Potassium -does it go in or out? Sodium -does it go in or out? Kin K goes in so Na must go out of the cell
9. Another way to think of it Life began in the sea The sea is very salty Salt has a tendency to enter the organisms/cells so we tend to be bathed in it Na tends to enter the cells so we must find a way to get rid of it Pump Na+ out of cell
10. Na+/K+ ATPase pump Notice #’s Moves 3 Na+ outside Moves 2 K+inside mnemonic- 2 letters in “in” and 3 letters in “out” Creates a charge difference Inside becomes negative Cell becomes polarized Can conduct electricity Called electrogenic pump Fig. 3.19 Solute Pumping
12. Na+/K+ ATPase pump Regulation of cell volume Where Na+ goes water follows Prevents the cell from swelling Fig. 3.19 Solute Pumping
13. Na+/K+ ATPase pump Secondary Active Transport e.g. sodium glucose transport protein (SGLT) Pump maintains low intercelluar Na+ levels Pump on basal end SGLT, in bringing Na back into the cell (down concentration gradient) , carries glucose with it SGLT on apical end Saves glucose from being dumped out of the body with urine Fig. 3.20 Solute Pumping Na levels low
14. Na+/K+ ATPase pump Heat Production Thyroid hormone stimulates cells to make more Na+/K+ ATPase pumps As they use ATP they release heat Fig. 3.19 Solute Pumping
15. Na+/K+ATPase pump Maintain Membrane Potential Established concentration gradients for Na+ and K+ across the membrane Also, 3 Na+ out and only 2 K+ in Charges of cell Crucial for excitable cells Like two poles of a battery Solute Pumping Nerve Cell
16. Introduction Energy is required for this process Movement of large macromolecules Types defined by the direction of movement Endocytosis Intake Exocytosis Output (e.g. secretion or excretion) Fig. 3.21 Bulk Transport
17. Endocytosis Three different types Phagocytosis Pinocytosis Receptor mediated endocytosis Fig. 3.21 Bulk Transport
18. Phagocytosis Literally means cell eating Usually a protective function Not all cells are phagocytic May bring in cell debris for clean up Fig. 3.21 Bulk Transport
20. Phagocytosis Extends pseudopods around the particle Pseudopods meet and package the material into a vessel (phagosome) Processes ingested material by fusion of phagosome with lysosome (phagolysosome) Residue is released by excretion (via exocytosis) Can go into blood and be filtered by the kidney Fig. 3.21 Bulk Transport
21. Phagocytosis Phagocytes Cells’ function is phagocytosis Found in almost every tissue compartment but only in specialized cells Lungs, for example, are rich in macrophages which are phagocytes Fig. 3.21 Bulk Transport
22. Pinocytosis Pino = tiny “cell drinking” Little pockets or divots form invaginations in the membrane Typically get this occurring in all human cells Extracellular fluid with whatever molecules were there at the time Bulk Transport http://academic.brooklyn.cuny.edu/biology/bio4fv/page/endocytb.htm
23. Receptor Mediated Endocytosis More selective than the other types Specific molecules without a lot of fluid Particles bind to specific receptors Membrane protein called clatharin When the clatharin and LDL’s (for example) are taken inside there is a clatharin coated vesicle Can serve as an address label to tell it where to go in the cell Fig. 3.22 Bulk Transport
24. Receptor Mediated Endocytosis Example is LDL (low density lipoproteins) and insulin Familial hypercholesterolemia Low number of LDL receptors so the cholesterol stays in the blood 1200 mg/dL Can have heart attacks before age 20 and usually die before age 30 Fig. 3.22 Bulk Transport
25. Exocytosis Secreting or excreting materials from the cell e.g. release of insulin, milk release from breast tissue, hormone release Like endocytosis in reverse Both endocytosis and exocytosis subtract from and add to the cell membrane so the amount is relatively constant Fig. 3.24 Bulk Transport
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27. ID 12051--- where the last three is your test number Your lab section you attend: A=001, B=002, etc. A list will be on the exam.
