Membrane Transport Solution homogeneous mixture of two or
Membrane Transport • Solution = homogeneous mixture of two or more components; ex: air (mixture of gases), seawater (water and salts) • Solvent = dissolving medium; ex: water • Solute = substances found in smaller amounts in the solvent. ; ex: sugar, salt • Intracellular fluid found inside the cell • Interstitial fluid bathes the outside of the cell
• Selective permeability = a barrier allows some substances to pass through while excluding others. • Two types of transport: Passive - No energy (ATP) required - High low - ex: diffusion osmosis facilitated diffusion filtration Active - energy (ATP) required - Low High - ex: solute pumping bulk transport endocytosis phagocytosis pinocytosis
Passive Transport • Diffusion = molecules move from high low concentrations. Ex: air freshener in a room, tea in a cup. • Osmosis = diffusion of water through a membrane ex: hypotonic, hypertonic, isotonic. • Facilitated Diffusion = a protein helps carry large molecules across the membrane.
• Filtration = water and solutes are forced through a membrane by fluid pressure. ex: blood, kidney function
Active Transport • Solute pumping = ATP is needed to move molecules from low high concentrations using a protein carrier ATP
• Bulk Transport: – Exocytosis = ATP used to move substances out of the cell • Hormones, wastes are packaged by the golgi apparatus into a membrane sac • This sac fuses with the cell membrane and expels the contents
• Endocytosis = ATP used to move substances into the cell – Substances are enclosed in a membrane vesicle – This vesicle fuses with a lysosome and the contents are digested – Ex: phagocytosis by the white blood cells “eating solids” – Ex: pinocytosis “drinking liquids” used in absorption by the cells
- Slides: 7