1. Fluid Mosaic Model: Backbone made of lipid bilayer (hydrophillic outside: interacts with watery environment & hydrophobic inside: barrier to water/nonpola)

2. Specialized Membrane Structures: microvilli, membrane-membrane adhesions, and membrane junctions

Backbone of Fluid Mosaic Model;

1. Phospholipid: hydrophillic (phosphate) outside- interacts with watery environment & hydrophobic (tails) inside- barrier to water/nonpolar;

2. Cholesterol: flat-plane molecule that stiffens P.M.

3. Membrane Proteins: Integral (imbedded in membrane/channels) & Peripheral (internal or external aspects of membrane/receptors or enzymes)

4. CHO attachments: Glycolipid (carb-lipid) & Glycoprotein (carb-protein)

5. Lipid Rafts: 20% of outer membrane; involved in cell signaling

1. Microvilli: folds of P.M; held in place by actin (microfilament); increase S.A; important for absorption

2. Membrane-Membrane Adhesions: Glycocalyx (glycoproteins and glycolipids) are polar sugars that can interact with neighboring structures; P.M has Wavy Contours (not straight)-grooves fit together

3. Membrane Junctions: Tight Junctions- prevent material from coming in between cells (prevents invasion); Desmosomes- (linker proteins & keratin/intermediate filaments) provide integrity/resist torsion (ex: uterus and epidermis); Gap Junctions- communication NOT integrity, action potential propagation in smooth muscle

1. Transport Processes: Passive & Active

2. Cell-Cell Adhesion & Interaction: Tight junction, desmosome, glycocalyx (anchoring/adhesion or migration/movement of cells during development or movement of certain immune cells along tissues)

3. Cell-Environment Interaction: cell has RECEPTORS on membrane proteins waiting to binds with particular LIGAND which is an environmental substance (ex: hormone, drug, or neurotransmitter); Ligand bind= change of metabolic activity

• Catalytic proteins (enzymes)
• Channel Linked
• G-Protein Linked
• Second Messengers

Pass message from membrane protein to intracellular protein which will then execute the command from the original ligand

Uses G proteins to affect signaling, causing cascade of events to the final cellular event (involves a 2nd messenger)

Transmembrane (integral) proteins that open or close in response to specific signal; often an ion channel/ligand often a neurotransmitter

Binding of ligand causes receptors to catalyze a reaction, ex: insulin receptor pulls glucose into cell

1. Primary Active Transport: ATP required; moves molecules against concentration gradient (symports or antiports/move 2 in dif directions)

2. Secondary: after concentration gradient is set up by P.A.T., diffusion of transported substance can occur, dragging along another molecule with it down its C.G.

3. Vesicular Active Transport: requires ATP; movement of vesicles to and from a membrane, content then passively diffused across membrane

1. Simple Diffusion: substances move from h-l concentration across membrane

2. Osmosis: diffusion of water from h-l concentration of water or l-h particle concentration

3. Facilitated Diffusion: involves protein transport proteins (carrier-mediated or channel-mediated protein); both still move from h-l con

4. Filtration: water & solutes pushed through membrane along pressure gradient (h-l)

1. Osmotic: pressure that resists further water entry into chamber due to osmosis

2. Hydrostatic: pressure that is exerted by fluid on the walls of a chamber that enclose it

Altering cells water volume changes shape

1. Isotonic: Concentration same inside as outside of cell; no net water movement; retains current shape

2. Hypotonic: Solution outside cell is less concentrated; water moves into cell; cell swells

3. Hypertonic: Solution outside cell is more concentrated; water moves out of cell; cell shrinks

1. Exocytosis: contents released to ext

2. Endocytosis: contents sucked into int; 3 types:

• Phagocytosis- P.M. engulfs particle that is outside
• Pinocytosis- vesicle brings in fluid (nutrients)
• Receptor-mediated endocytosis- receptor on P.M. binds w/molecule and then endocytotic vesicle is brought into cell w/ molecule attached to it