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Transport

Transport. Passive and Active. Passive Transport. Passive transport is any transport that occurs without the use of energy. Ex: Diffusion Osmosis Facilitated diffusion Ion Channels. Diffusion.

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Transport

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  1. Transport • Passive and Active

  2. Passive Transport • Passive transport is any transport that occurs without the use of energy. • Ex: • Diffusion • Osmosis • Facilitated diffusion • Ion Channels

  3. Diffusion • The movement of molecules from an area of higher concentration to an area lower concentration. • Concentration gradient • Driven by kinetic energy • Dynamic equilibrium • CO2 and O2

  4. Osmosis • The process in which water molecules diffuse from areas of higher concentration to lower concentration. • Depends on the concentration of the solutes found in the water on the two sides of the membrane.

  5. Isotonic Iso- equal / the same • When the concentration of solutes outside and inside the cell are equal, the outside solution is said to be isotonic to the cell. • The water moves into and out of the cell at even rates.

  6. Hypotonic Hypo – under / beneath • When the concentration of solute is lower outside of the cell than the concentration of solute inside the cell. The solution outside the cell is said to be hypotonic. • The water will move into the cell until equilibrium is reached.

  7. Hypertonic Hyper – above / excessive • When the concentration of solute is higher outside of the cell than the concentration of solute inside the cell. The solution outside the cell is said to be hypertonic. • The water will move out of the cell until equilibrium is reached.

  8. Cells and Osmosis • Contractile Vacuole – organelle that takes up water from the cytoplasm and then pump it out of the cell. Requires energy. • Turgor Pressure – pressure that water molecules exert against the cell wall. • Plasmolysis – When plant cells do not receive enough water and the cell membrane shrinks away from the cell wall. The plant cell shrivels. • Cytolysis – When animal cells are left in hypotonic solutions, water continues to enter until the cell bursts.

  9. Tonicity • Tonicity problems let you figure out how water will diffuse based on the % concentration of a solution. • Ex: • If the solution in a cell is 2% solute, it would be 98% water. That cell is placed in a solution that was 5% solute and therefore 95% water. • Is the solution that the cell is placed in hypotonic, isotonic, or hypertonic? • Is the cell going to gain or lose water? • If the cell is an animal cell, what would the cell look like after it sat in the solution for an extended period of time?

  10. Facilitated Diffusion and Ion Channels • Facilitated diffusion – movement of molecules across a membrane with assistance from proteins in the membrane. Energy is still not being used. • Performed by carrier proteins (type of integral protein) • Aid in movement from higher concentration to lower concentration regardless of movement into or out of the cell. • Glucose uses carrier proteins • Ion Channels • Transport ions from higher concentration to lower concentration • Na+, K+, Ca2+, and Cl- • Specific for each ion • Gated

  11. Active Transport • Movement of molecules from lower concentrations to higher concentrations with the use of energy. • Ex: • Cell Membrane Pumps • Movement in vesicles (small spherically shaped sacs surrounded by a single membrane) • Endocytosis • Exocytosis

  12. Cell Membrane Pumps • Carrier proteins that use energy to “pump” molecules from one area to another. • Use energy – ATP (Adenosine Triphosphate) • Ex : Na+ /K+ Pump • Need a higher concentration of Na+ outside the cell and a higher concentration of K+ inside the cell. • 3 Na+ bind to the pump inside the cell, the pump expels them outside of the cell. This builds up a high concentration of Na+ outside the cell. • The pump then binds 2 K+ located outside the cell and pushes them through the membrane into the cell. • This creates an electrical gradient across the cell where the inside of the cell is negative in comparison to the outside. • Allows for the sending and receiving of electrical impulses across the cell.

  13. Na+/K+ Pump

  14. Endocytosis • When substances are brought into the cell • There are two types • Pinocytosis - small particles and fluid • Phagocytosis - large particles or entire cells • Used by cells as a way to eat • Used by the immune system to take in bacterial cells and dead tissues/debris to be destroyed by the lysosome

  15. Exocytosis • The process by which the cell exports materials out of the cell. • Items for export are first packaged in the Golgi apparatus • Releases items such as: proteins, hormones, waste, or toxins

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