1.4 MEMBRANE TRANSPORT
GUIDANCE:- OSMOSIS EXPERIMENTS ARE A USEFUL OPPORTUNITY TO STRESS THE NEED FOR ACCURATE MASS AND VOLUME MEASUREMENTS IN SCIENTIFIC EXPERIMENTS.
Understandings Particles move across membranes by simple diffusion, osmosis, and active transport.
The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells.
Applications/Skills A: Structure and function of sodium-potassium pumps for active transport and potassium channels for facilitated diffusion in axons.
A: Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.
S: Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions.
PASSIVE TRANSPORT Needs a concentration gradient Does not require energy Diffusion Facilitated Diffusion Osmosis
DIFFUSION Particles move from higher concentration to lower concentration
Small particles, gases, nonpolar molecules diffuse across membranes easily
http://www.dbriers.com/tutorials/wp-content/uploads/2012/11/PassiveTransport.jpg
FACILITATED DIFFUSION Does not require energy Involves carrier proteins in a membrane that change shape in order to transport substance
Rate levels off when saturation of carriers occurs
http://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/0306_Facilitated_Diffusion.jpg/474px-0306_Facilitated_Diffusion.jpg
OSMOSIS Passive movement of water across a semipermeable membrane from an area of high concentration to low concentration
Result of a difference in solute concentrations on either side of the membrane
Water moves from hypotonic solution to hypertonic solution Hypertonic: higher concentration of solutes Hypotonic: lower concentration of solutes Isotonic: equal concentrations of solutes (no net movement)
http://marklchampion.files.wordpress.com/2012/07/anp2tri1qfyc1osmosis.jpg
ACTIVE TRANSPORT Requires energy (ATP) Moves substances against the concentration gradient
http://3.bp.blogspot.com/-_L78tIYKOJs/ULjsjbaDkPI/AAAAAAAAKpI/emUgi13Z3T0/s1600/active+transport.png
SODIUM-POTASSIUM PUMP
ENDOCYTOSIS
http://eng.thesaurus.rusnano.com/upload/iblock/15d/endocidoz_1.jpg
EXOCYTOSIS
http://encyclopedia.lubopitko-bg.com/images/Exocytosis_01.jpg
HOMEWORKVocabPassive transportActive transportOsmosisHypertonicHypotonicIsotonicIntracellularExtracellularInterstitial
Sodium-potassium pumpExocytosisPhagocytosisPinocytosis
Other Pg 34- Challenge Yourself 6-13 Pg 37- Exercises 16-18