CELL BIOLOGY - Overview: A. Membranes - how stuff get in/out of cells 1. Structure 2. Functions

CELL BIOLOGY - Overview: A. Membranes - how stuff get in/out of cells 1. Structure 2. Functions 3. Types of "transport"

LE 7-11a Molecules of dyeMembrane (cross section) WATER Net diffusion Equilibrium Diffusion of one solute Types of "transport" - DIFFUSION

LE 7-11b Net diffusion Equilibrium Diffusion of two solutes Net diffusion Equilibrium Types of "transport" - DIFFUSION

LE 7-12 Lower concentration of solute (sugar) Higher concentration of sugar Same concentration of sugar Selectively permeable mem- brane: sugar mole- cules cannot pass through pores, but water molecules can H2OH2O Osmosis - OSMOSIS: diffusion of water across a semi-permeable membrane from HI to LO water potential Water Potential: as solute conc. increases as pressure increases

LE 7-13 Animal cell Lysed H2OH2O H2OH2O H2OH2O Normal Hypotonic solution Isotonic solutionHypertonic solution H2OH2O Shriveled H2OH2O H2OH2O H2OH2O H2OH2O Plant cell Turgid (normal) FlaccidPlasmolyzed 9% Salt 1% 9% Salt 9% 15%

LE 7-15a EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM Types of "transport" - FACILITATED DIFFUSION - for big or charged stuff movement in the direction of the concentration gradient

LE 7-15b Carrier protein Solute Types of "transport" - FACILITATED DIFFUSION - for big or charged stuff movement in the direction of the concentration gradient

LE 7-17b ATP Types of "transport" - ACTIVE TRANSPORT AGAINST concentration gradient MUST use ENERGY Makes cell DIFFERENT FROM the environment.

LE 7-16 Cytoplasmic Na + bonds to the sodium-potassium pump CYTOPLASM Na + [Na + ] low [K + ] high Na + EXTRACELLULAR FLUID [Na + ] high [K + ] low Na + ATP ADP P Na + binding stimulates phosphorylation by ATP. Na + K+K+ Phosphorylation causes the protein to change its conformation, expelling Na + to the outside. P Extracellular K + binds to the protein, triggering release of the phosphate group. P P Loss of the phosphate restores the protein’s original conformation. K + is released and Na + sites are receptive again; the cycle repeats. K+K+ K+K+ K+K+ K+K+ K+K+

LE 7-17 Diffusion Facilitated diffusion Passive transport ATP Active transport

LE 7-18 H+H+ ATP CYTOPLASM EXTRACELLULAR FLUID Proton pump H+H+ H+H+ H+H+ H+H+ H+H – – – – –

LE 7-19 H+H+ ATP Proton pump Sucrose-H + cotransporter Diffusion of H + Sucrose H+H+ H+H+ H+H+ H+H+ H+H+ H+H – – – – – –

LE 7-20a CYTOPLASM Pseudopodium “Food” or other particle EXTRACELLULAR FLUID Bacterium Food vacuole An amoeba engulfing a bacterium via phagocytosis (TEM) Pseudopodium of amoeba 1 µm Food vacuole PHAGOCYTOSIS Types of "transport" - Phagocytosis and Pinocytosis

LE 7-20b Plasma membrane Pinocytosis vesicles forming (arrows) in a cell lining a small blood vessel (TEM). 0.5 µm Vesicle PINOCYTOSIS Types of "transport" - Phagocytosis and Pinocytosis

LE 7-20c Receptor RECEPTOR-MEDIATED ENDOCYTOSIS Ligand Coated pit Coated vesicle Coat protein Coat protein Plasma membrane 0.25 µm A coated pit and a coated vesicle formed during receptor- mediated endocytosis (TEMs).