1. Transport Chapter 7 & 36

2. What you need to know! The role of diffusion (osmosis), active transport, and bulk flow in the movement of water and nutrients in plants. How electrochemical gradients are formed.

3. Movement of Substances Bulk Flow: Collective movement of substances in the same direction in response to a force Example: blood flow (force = heart) Movement of substances may be active or passive. Active movement requires energy (ATP) Passive transport: movement of substances down a concentration gradient (high  low)

4. Passive Transport 1.Simple diffusion: gases go between phospholipids (no proteins needed) 2.Osmosis: water facilitated by aquaporins 3.Dialysis: diffusion of solutes across a semipermeable membrane that allows small molecules through and blocks large ones: dialysis tubing, kidney, dialysis of patients with kidney problems 4.Plasmolysis: net movement of water out of plant cells leading to collapse of cell Wilting plants, drop in turgor

5. Passive Transport 5.Facilitated Diffusion: diffusion of solutes through channel proteins/pores Examples: ions, sugars, proteins, AA 6.Counter current exchange: exchange of substances between two oppositely running bulkflows, maximizing exchange Example: waterflow and bloodflow through fish gills

6. Active Transport Movement of solutes against a concentration gradient using transport proteins Requires the expenditure of ATP 1.Electrochemical gradient: Na/K pump in nerve cells builds up not only a gradient of Na and K, but also a charge across the membrane Resting potential = -60mV

7. Cotransport: coupled transport Couples transport “downhill” with transport “uphill” Example: H+ gradient over plasma membrane is used to move sucrose into cells Na/Glucose co transporter Example: salts in Gatorade cotransport with glucose

8. Vesicular Transport Uses membrane bound vesicles to move large substances across membrane 1.Exocytosis: fusing of vesicle with membrane, releasing contents outside of cells Example: secretion of hormones, enzymes, neurotransmitters in synapses 2.Endocytosis: pinching in of membrane around molecules leading to internalization Example: phagocytosis, pinocytosis, receptor mediated endocytosis, endosymbiotic Theory