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Transport Mechanisms through Cell Membranes Chapter 3.3. Passive vs. Active Transport. Selectively Permeable = cell membrane will only allow some things through!. Large macromolecules and charged ions can NOT get through the lipid bi-layer!!!. Passive Transport.
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Transport Mechanisms through Cell MembranesChapter 3.3 Passive vs. Active Transport
Selectively Permeable = cell membrane will only allow some things through! • Large macromolecules and charged ions can NOT get through the lipid bi-layer!!!
Passive Transport • Movement from high to lowconcentrations. • Does NOT require energy. • 3 Types of Passive Transport: • Diffusion • Osmosis • Facilitated Diffusion • Filtration
Diffusion • Movement of molecules from high concentration to low concentration.
Osmosis • Diffusion of WATER!!!!! • What happens when you eat popcorn? • Why do your fingers get wrinkles when you swim too long? • Have you ever put salt on a slug???
Facilitated Diffusion • Diffusion with the help of “channel” proteins. - Usually because molecules are too big or have a charge and can not go through the membrane alone.
Three Types of Solutions (Water + Solute/stuff) • Hypertonic • Solutions that have MORE “stuff” and less water than the cell. • Water will move out of cell, causing it to shrivel.
Hypotonic • Solution has LESS “stuff” and more water than the cell. • Water will move INTO cell, causing cell to burst.
Isotonic • Solution has the SAME amount of “stuff” and water as the cell. • There is no net gain or loss of water from the cell. • This is the IDEAL solution that your body tries to maintain!!!!
Filtration • Separation of small particles, due to hydrostatic (water) pressure through a selectively permeable membrane.
Active Transport Movement from low to highconcentration. Requires ENERGY. 3 Types of Active Transport: - Protein PUMPS - Endocytosis (Phagocytosis) - Exocytosis
Protein “Pumps” Movement of molecules from Low concentration into High concentrations, requiring energy.
Endocytosis or Phagocytosis • Active transport of large particles INTO the cell, by surrounding them with the cell membrane.
Exocytosis • Active transport of substances OUT of the cell using the cell membrane.
Concentration Mountain Active Transport Passive Transport DiffusionOsmosisFacilitated Diffusion Protein pumpsEndocytosisExocytosis Uses Energy No Energy