Diagram of a Membrane

Membranes Draw and label a diagram of a membrane Extracellular Intracellular Thickness: 7.5 nm Explain how properties of phospholipids maintain membrane structure • Structure of phospholipid (hydrophilic/polar head & hydrophobic/non-polar tails) • Arrangement in bilayer (hydrophobic tails face inwards; hydrophilic heads face surrounding fluid) • Properties of membrane (hydrophobic interactions, fluidity, saturated vs unsaturated fatty acids) Functions of membrane proteins Define diffusion & osmosis Remember: TRACIE Diffusion: Net movement of molecules from Transport (active vs facilitated diffusion) Receptors (e.g. for hormones & neurotransmitters) Adhesion (attachment sites for ECM) Cell Recognition (MHC molecules; HLA antigens) Intercellular Joining (e.g. tight junctions) Enzymatic Activity (e.g. ATP synthase) a region of high to low concentration, until equilibrium is reached Osmosis: Net movement of water molecules across a semi-permeable barrier from a region of low solute to high solute concentration, until equilibrium is reached Explain passive transport Explain active transport Remember: Along gradient, no ATP Remember: Against gradient, uses ATP Simple: Small or lipophilic molecules cross freely • Molecule binds to surface of protein pump Examples: O2, CO2, H2O, steroids • Hydrolysis of ATP causes a conformational change in protein pump Facilitated: Larger, polar substances cross via protein channels (interior linings are polar) Examples: Ions, glucose, sucrose Explain vesicle transport 2. rER • Molecule translocated to interior surface Examples: Na+/K+ pump Describe membrane fluidity 4. Plasma membrane 1. Nucleus 3. Golgi • Change shape (membrane is amorphous) • Break and reform (weak hydrophobic forces) • Cytosis (endocytosis vs exocytosis)