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Cellular Transport. Functions of the cell membrane. 1. Provides boundary for cell 2. Selectively permeable- only allows certain things to pass through- “Picky” Ex. Window screen 3. Maintains homeostasis: balance within the cells. Relate the structure of the cell membrane to its function.
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Functions of the cell membrane. 1. Provides boundary for cell 2. Selectively permeable- only allows certain things to pass through- “Picky” Ex. Window screen 3. Maintains homeostasis: balance within the cells
Relate the structure of the cell membrane to its function. • Membrane is a lipid bilayer • fluid-mosaic model • Phospholipids: fatty areas that attract (hydrophillic) and repel (hydrophobic) water • Embedded proteins: “bouncers” • Decide who goes in & out • Markers for recognition
Diffusion Osmosis Diffusion movement of particles from high to low concentration Ex. Perfume & Body odor High concentration OSMOSIS movement of water from high to low concentration. Both Go through bilayer Do NOT require cell energy (passive transport) Move until equilibrium is reached Low concentration
Compare the three types of solutions. • ISOTONIC: same strength • particles outside = particles inside • ISO- means “equal to” • Movement into cell= movement out of cell
HYPOTONIC:concentration of dissolved substances is lower outside cell than inside cell • HYPO means “below strength” • Water will move INTO cell causing it to swell (it always moves to where there is more substances) • Cells could rupture if the cell takes in too much water • This increases pressure inside of cell (TURGORPRESSURE)
HYPERTONIC: concentration of dissolved substances is higher outside the cell • HYPER means “above strength” • Water rushes OUT of cell causing it to shrivel (water rushes to where there is more substances) • Can result in PLASMOLYSIS in plants which causes wilting
FACILITATED DIFFUSION: • type of diffusion since movement is from high to low concentration, but this type goes through a protein channel rather than bilayer. • Also Passive Transport • Proteins –picky “bouncers” Glucose molecules High Concentration Protein channel Low Concentration
Molecule to be carried • ACTIVE TRANSPORT: transport against concentration gradient; goes from low to high concentration • Go through protein channel • This requires energy to move them into cell; ex: Na-K pump Low Concentration High Concentration Molecule being carried Energy
Types of active transport: • ENDOCYTOSIS: cells take in large clumps of substances • Phagocytosis: “cell eating” take in food • Pinocytosis: “cell drinking” take in water • EXOCYTOSIS: cells move substances out(exit) ex: wastes
Summary • Diffusion & Osmosis/ high to low conc./ go in between phospholipid spaces/ no energy= Passive transport • Facilitated Diffusion- high to low/ no energy/ goes through protein • Active transport- low to high conc./ requires energy/ goes through protein • Ex. Party ` 1. Air coming into a window screen 2. Someone opens the door & you walk through (door represents protein) 3. someone goes through the back door that is already open *coming in=Endocytosis going out= Exocytosis