1. Cell Membrane structure and transport

2. Cell membranes of cheek cells,
400X magnification

3. Cell membrane (http://www.jdaross.mcmail.com/cell2.htm)

4. Cell membrane at 240,000 X magnification(

5. Cell Membrane (plasma membrane)
Separates living cell from nonliving surroundings
Selectively permeable
(semi-permeable)
Fatty acid
tails

6. Polymer Carbohydrates Lipids Proteins Nucleic acids monomers examples
Starches, cellulose,
Pasta, potatoes, etc.
Fats, oils, waxes
Meat, muscle tissue, enzymes, hair, etc.
DNA & RNA
Simple sugars
Glycerol & fatty acids
Amino acids
nucleotides
Carbohydrates
Lipids
Proteins
Nucleic acids

7. Membrane Structure Phospholipid bilayer Proteins Cholesterol
Integral protein
Peripheral protein
Cholesterol
Carbohydrates

8. Phospholipid bilayer Phosphate group (PO4-3) Lipid tail
Polar, Hydrophilic
Lipid tail
Non-polar, hydrophobic
Unsaturated fat: kink, don’t pack tight
Saturated fat: lie straight, pack tight

9. Cholesterol Breaks up phospholipid tails
More of them in cold- weather cells, fewer in tropical cells
Makes the cell membrane
More fluid in colder temperatures
More rigid in warmer temperatures

10. Proteins Two main kinds Two main functions Integral Peripheral
Lie within the membrane
Transmembrane proteins span the entire core
Peripheral
Attach to external surface by weak bonds
Two main functions
Transporters
Receptors

11. Carbohydrates
Short sugar chains = oligosaccharides. covalently bonded to lipids or proteins
Glycolipid
Glycoprotein
Function
Cell to Cell recognition

12. FLUID MOSAIC MODEL OF THE CELL MEMBRANE
The parts are dynamic…they move around and change positions (the membrane is FLUID)
The cell membrane is NOT a single, solid structure—it is made up of many smaller parts (it is a MOSAIC)
hence, the name…
FLUID MOSAIC MODEL OF THE CELL MEMBRANE

13. Transport Diffusion Active Transport Endocytosis Exocytosis Osmosis
Facilitated Diffusion
Active Transport
Endocytosis
Phagocytosis
Pinocytosis
Exocytosis

14. Diffusion
Movement of molecules from areas of high concentration to areas of low concentration.
Passive, requires no extra energy
Small, non polar molecules O2
CO2

15. Osmosis iso- = equal hyper- = above/over hypo- = below/under
Diffusion of water through a membrane
from an area of high concentration to an area of low concentration
Isotonic
Hypertonic
Hypotonic
No extra energy required
iso- = equal
hyper- = above/over
hypo- = below/under

16. Plasmolysis and Turgor
The shrinking of a plant cell when placed in a hypertonic environment. Cell membrane pulls away from the cell wall.
Turgor pressure
When a cell is full of water. The water vacuole exerts pressure against the walls
Helps hold the plant up.

19. Facilitated Diffusion
Molecules moving from high to low concentration with help.
Use Channel or Carrier protein
Aquaporins
Requires no energy
Large, polar or ionic molecules.
Na+
Ca+2
Glucose

20. Active Transport
Movement of molecules against a concentration gradient.
Requires energy
Na+/K+ pump
Ca+2 pump in muscle cells
H+ pump (plants, fungi,bacteria)
Builds electrochemical gradient

21. CoTransport
A substance that has been actively pumped to one side, builds a gradient. This gradient, potential energy, can do work as it leaks back across. Escorts, in this case, glucose
Na+ with glucose
Why should you drink gatorade or powerade when dehydrated or pedialyte when you have the flu?

23. A Represents?
Represents?

24. Endocytosis
Cell takes in macromolecules or large particles by forming new vesicles from the plasma membrane.
Three kinds
Phagocytosis
Pinocytosis
Receptor-mediated endocytosis

25. Endocytosis Phagocytosis
Cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane enclosed sac.
Amoeba
White Blood Cell
Macrophage

26. Endocytosis Pinocytosis “Cell drinking”
Unspecific as it takes in any solute along with the solvent

27. Endocytosis Receptor mediated endocytosis
Specific substances “ligands” bind to receptors on cells.
Receptors are in areas called “pits”.

28. Exocytosis
The opposite of endocytosis.
Cell gets rid of substances by forming a membrane around the substance. The bubble of material moves to the cell membrane and is released.