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TRANSPORT ACROSS MEMBRANES

TRANSPORT ACROSS MEMBRANES. Learning Goal: . Learning Goal:. I can explain the dynamics of passive transport and active transport and the processes of endocytosis and exocytosis of large particles an. PASSIVE TRANSPORT.

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TRANSPORT ACROSS MEMBRANES

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  1. TRANSPORT ACROSS MEMBRANES Learning Goal:

  2. Learning Goal: I can explain the dynamics of passive transport and active transport and the processes of endocytosis and exocytosis of large particles an

  3. PASSIVE TRANSPORT • The movement of materials across a cell membrane without the expenditure of energy • Three types: Diffusion, Osmosis and Facilitated Diffusion

  4. Diffusion • The movement of molecules from an area of high concentration to an area of low concentration • The rate of diffusion is affected by, concentration, temperature and pressure

  5. Osmosis: • The diffusion of water molecules across a selectively permeable membrane. • The cell membrane is a selectively permeable membrane. Some molecules can pass through while other cannot • Other types of membranes are impermeable and permeable • Water will move from an area of high concentration to an area of low concentration

  6. Movement of Water • Cells need water to survive. Ideally cells are bathed in • Isotonic solutions • A solution where the concentration of solute molecules outside the cell is equal to the concentration of solute molecule inside the cell • Any water movement into the cell is balanced by the water moving out of the cell

  7. Hypotonic solution • A solution where the concentration of solutes outside a cell is LOWER than that found inside the cell. • There is more water OUTSIDE the cell, so it moves in • More water entering than leaving • Cell expands

  8. Hypertonic solutions • A solution where the concentration of solutes outside a cell is HIGHER than that found inside the cell. • There is more water INSIDE the cell, so it moves OUT • More water leaving than entering • Cell shrinks

  9. Facilitated Diffusion: • Protein (helper) carriers help to speed up the movement of molecules already moving • These protein carriers are located in the cell membrane • Cell selects what it needs and if it needs it quickly, the protein carrier moves it along

  10. ACTIVE TRANSPORT • This type of transport involves the use of the cells energy to move materials across a cell membrane, AGAINST the concentration gradient • Cells take in smallersolutes by means of transport carrier molecules, but many that are essential for life will not pass through the pores of the cell membrane. • These larger molecules require Membrane Assisted Transport.

  11. Membrane Assisted Transport • Endocytosis • The process by which cells ingest materials by extending their cytoplasm around the particle 3 Types • Pinocytosis, cell engulf liquid droplets • Phagocytosis, cell engulf solid particles • Receptor-Mediated endocytosis

  12. Membrane Assisted Transport • Exocytosis • The process by which large molecules held within the cell are transported to the external environment. In animal cells, exocytosis provides a mechanism for releasing hormones, neurotransmitters, digestive enzymes.

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