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

Videos

• http://www.youtube.com/watch?v=ULR79TiUj80

• http://www.youtube.com/watch?v=4gLtk8Yc1Zc&feature=related

• http://www.youtube.com/watch?v=W6rnhiMxtKU