Membrane Structure & Molecule Transport Part 2 AP Biology Membrane Structure & Molecule Transport Part 2
Cell Membrane
Tunnel Transport proteins EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM
“Grabber” Transport proteins Carrier protein Solute
Diffusion
Osmosis
. Hypotonic solution Isotonic solution Hypertonic solution Animal cell H2O H2O H2O H2O Lysed Normal Shriveled Plant cell H2O H2O H2O H2O Turgid (normal) Flaccid Plasmolyzed
Positive Pressure Potential
Negative Pressure Potential
Solute Potential ΨS = -iCRT -i (ionization constant) C (molar concentration) R (pressure constant) T (temperature in Kelvin)
Total Water Potential problems
Facilitated Diffusion EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM
Active Transport Cytoplasmic Na+ bonds to the sodium-potassium pump EXTRACELLULAR FLUID [Na+] high [K+] low Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+ [Na+] low [K+] high ATP P Na+ P CYTOPLASM ADP Cytoplasmic Na+ bonds to the sodium-potassium pump Na+ binding stimulates phosphorylation by ATP. Phosphorylation causes the protein to change its conformation, expelling Na+ to the outside. K+ K+ K+ K+ K+ P P K+ Extracellular K+ binds to the protein, triggering release of the phosphate group. Loss of the phosphate restores the protein’s original conformation. K+ is released and Na+ sites are receptive again; the cycle repeats.
Cell Voltage Gradient
Proton pumps
Proton pumps and co-transport
Phagocytosis & Pinocytosis
RECEPTOR-MEDIATED ENDOCYTOSIS . RECEPTOR-MEDIATED ENDOCYTOSIS Coat protein Receptor Coated vesicle Coated pit Ligand A coated pit and a coated vesicle formed during receptor- mediated endocytosis (TEMs). Coat protein Plasma membrane 0.25 µm