Plasma Membrane Structure and Role in Cellular Transport

Membrane Structure Phospholipid bilayer Protein Fluid Mosaic Model Hydrophobic Hydrophylic

Membrane Proteins Transport Enzyme Signal transduction Cell recognition Cell joining Attachment to cytoskeleton and ECM

External to Plasma Membrane Prokaryote –Cell wall –Peptidoglycan Plant Cell –Cell wall –Cellulose Animal Cell –Extra Cellular Matrix

Extracellular Matrix Integrin Fibronectin Collagen Proteoglycan Microfilaments

Cell Junctions Tight Junction –Seal –actin Adherens junction –Cytoskeleton to ECM –Actin –integrin Desmosome –Rivet like –keratin

Transport Passive –Diffusion –Osmosis –Facilitated diffusion Active –Pump Bulk –Endocytosis –exocytosis

Diffusion Solute moves Net movement down a concentration gradient Endpoint equilibrium Oxygen Carbon dioxide

Osmosis Solvent moves Requires a semi permeable membrane Concentration gradient driven Endpoint equilibrium

Facilitated Diffusion Protein required Concentration gradient driven Net movement down the concentration gradient Endpoint equilibrium

Active Transport Requires membrane protein Requires ATP Pump Moves substances against a concentration gradient Ions

Bulk Transport Very large substances Requires use of vesicles Fusion with plasma membrane Endocytosis Exocytosis Phagocytosis pinocytosis

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