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