MEMBRANE TRANSPORT CELL PHYSIOLOGY MEMBRANE TRANSPORT Membrane transportmovement

MEMBRANE TRANSPORT

CELL PHYSIOLOGY: MEMBRANE TRANSPORT • Membrane transport—movement of substances into and out of the cell • Two basic methods of transport • Passive transport • No energy is required • Active transport • Cell must provide metabolic energy (ATP)

PASSIVE TRANSPORT • Diffusion • Particles distribute themselves evenly within a solution • Movement from high concentration to low concentration,

PASSIVE TRANSPORT • Diffusion 1. They are small enough to pas through pores 2. They can dissolve in fatty portion of membrane 3. They are assisted by membrane carrier

PASSIVE TRANSPORT • Simple Diffusion: unassisted • lipid-soluble materials / small enough to pass through membrane pores

PASSIVE TRANSPORT

ACTIVE TRANSPORT Extracellular fluid Na+ K+ Na+ P P Na+ K+ P K+ ATP ADP Binding of cytoplasmic Na + to the pump protein stimulates phosphorylation by ATP, which causes the pump protein to change its shape. The shape change expels Na+ to the outside. Extracellular K+ binds, causing release of the phosphate group. Loss of phosphate restores the original conformation of the pump protein. K + is released to the cytoplasm and Na+ sites are ready to bind Na + again; the cycle repeats. Cytoplasm

ACTIVE TRANSPORT: EXOCYTOSIS

ACTIVE TRANSPORT: ENDOCYTOSIS Extracellular fluid Cytoplasm Pit Extracellular fluid Plasma membrane Recycling of membrane and receptors (if present) to plasma membrane Ingested substance Transport to plasma membrane and exocytosis of vesicle contents Vesicle Lysosome Detachment of vesicle Plasma membrane (a) Vesicle containing ingested material Vesicle fusing with lysosome for digestion Release of contents to cytoplasm

ACTIVE TRANSPORT: ENDOCYTOSIS Phagocytosis Receptor-mediated endocytosis

CELL PHYSIOLOGY: MEMBRANE TRANSPORT • https: //www. youtube. com/watch? v=d. PKv. Hr. D 1 e. S 4 • https: //www. youtube. com/watch? v=Yfoi. Hrv 57 b 0