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Homeostasis and Transport across membranes. Ch5 p94. Types of Transport. Passive Transport Diffusion Osmosis Facilitated diffusion Active Transport Cell membrane pumps Endocytosis Exocytosis.
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Types of Transport • Passive Transport • Diffusion • Osmosis • Facilitated diffusion • Active Transport • Cell membrane pumps • Endocytosis • Exocytosis Movement across a membrane depends on BOTH the concentrations of particles AND theirsize, shape and if they dissolve in lipids!
Passive Transport • Diffusion – the movement of particles from an area of high concentration to an area of low concentration • Movement down its concentration gradient • Happens naturally due to kinetic energy of molecules • Dye in a glass of water (where would it happen faster – hot water or cold water?) • Movement of particles happens until EQUILIBRIUM is reached as long as the particles… …can move thru the substance or across the membrane
Passive Transport • Osmosis – the movement of WATER from an area of high concentration to low concentration • Hypertonic: get your energy OUT • Hypotonic: Hypo the Hippo • Isotonic: equal
http://www.youtube.com/watch?v=kkPiRT2ewVA&feature=related • http://www.youtube.com/watch?v=iG6Dd3COug4&NR=1
Passive Transport • Facilitated Diffusion – the movement of particles is assisted by carrier proteins in the cell membrane.
Active Transport • Cell Membrane pumps • Sodium (Na)-potassium (K) pumps • “Na Na NAAA Na, Na Na NAAA Na HEY HEY Good bye” • Our cells need the potassium in them. It doesn’t care if there isn’t a lot outside the cell, it just wants to bring in as much as it can. • Sodium sneaks in the cell, and isn’t needed. SO…the cell uses energy to kick out the Na and bring in the K
Active Transport • Endocytosis: endo=in cyto=cell • Pinocytosis “to drink” brings in fluid • Phagocytosis “to eat” brings in large particles or cells • The cell membrane forms a divit and wraps around until it connects on the other side, forming a vessicle.
Active Transport • Exocytosis: Exo=exit cyto=cell • When a vesicle that has formed in the cell, attaches to the cell membrane and opens up, releasing its contents out of the cell.