1. Warm-Up 1 Is the plasma membrane symmetrical? Why or why not?
What types of substances cross the membrane the fastest? Why?
Explain the concept of water potential. (Hint: Refer to Lab 1)

2. Warm-Up 2
What are glycoproteins and glycolipids and what is their function?
How do hydrophilic substances cross the cell membrane?
Why does water move through the bi-layer quickly?

3. Warm-Up 3
Side A in a U tube has 5M sucrose and 3 M glucose. Side B has 2 M sucrose and 1 M glucose. The membrane is permeable to glucose and water only. What happens to each side?

4. Warm-Up 4
Side A in a U tube has 3 M sucrose and 1 M glucose. Side B has 1 M sucrose and 3 M glucose. The membrane is permeable to glucose and water only. What happens to each side?

5. Cell Transport NOTES
Growth and dynamic homeostasis are maintained by the constant movement of molecules across membranes.

6. Passive Transport NO ENERGY needed!
Diffusion down concentration gradient (high  low concentration)
Eg. hydrocarbons, CO2, O2, H2O

8. Osmosis: diffusion of H2O

9. Importance: IMPORT of RESOURCES (nutrients, O2, H2O, etc.)
EXPORT of WASTES (CO2, etc.)

10. External environments can be hypotonic, isotonic or hypertonic to internal environments of cell.

11. Osmoregulation Control solute & water balance
Contractile vacuole: “bilge pump” forces out fresh water as it enters by osmosis
Eg. paramecium caudatum – freshwater protist

12. Facilitated Diffusion
4/15/2017
Facilitated Diffusion
Transport proteins (channel or carrier proteins) help hydrophilic or charged substance cross
(1) Provide hydrophilic channel or (2) loosely bind/carry molecule across
Eg. ions, polar molecules (glucose)

13. Glucose Transport Protein (carrier protein)

14. Active Transport
Where free energy is used by proteins embedded in membrane to MOVE molecules and / or ions to maintain homeostasis
Requires ENERGY (ATP)
Proteins transport substances against concentration gradient (low  high conc.)
Eg. Na+K+ pumps, proton pumps, endocytosis, exocytosis

15. Electrogenic Pumps: generate voltage across membrane
Na+/K+ Pump
Proton Pump
Pump Na+ out, K+ into cell
Nerve transmission
Push protons (H+) across membrane
Eg. mitochondria (ATP production)

16. Eg. sucrose-H+ cotransporter (sugar-loading in plants)
Cotransport: membrane protein enables “downhill” diffusion of one solute to drive “uphill” transport of other
Eg. sucrose-H+ cotransporter (sugar-loading in plants)

17. Passive vs. Active Transport
Little or no Energy
High  low concentrations
DOWN the concentration gradient
eg. diffusion, osmosis, facilitated diffusion (w/transport protein)
Requires Energy (ATP)
Low  high concentrations
AGAINST the concentration gradient
eg. pumps, exo/endocytosis

19. Bulk Transport
Transport of proteins, polysaccharides, large molecules, etc. from the external environment to the internal (and vice versa)
Endocytosis: take in macromolecules, form new vesicles
Exocytosis: vesicles fuse with cell membrane, expel contents

20. Endocytosis
Cell takes in macromolecules and particulate matter by forming new vesicles derived from the plasma membrane

21. Types: Phagocytosis: “cellular eating” - solids Pinocytosis:
“cellular drinking” - fluids
Receptor-Mediated Endocytosis:
Ligands bind to specific receptors on cell surface

22. Exocytosis
Internal vesicles fuse with the plasma membrane to secrete large macromolecules out of the cell.

23. Internal Membranes
Eukaryotic cells maintain internal membranes that partition the cell into specialized regions

24. Functions: Minimize competing interactions
Increased surface area where reactions can occur
Isolate specific enzymatic reactions
Organelles with internal membranes:
Endoplasmic Reticulum
Mitochondria
Chloroplasts
Golgi
Nuclear Envelope

26. Archaea and Bacteria
Lack internal membranes
Have a cell wall