PASSIVE VS ACTIVE TRANSPORT

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PASSIVE VS ACTIVE TRANSPORT
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PASSIVE TRANSPORT

• Requires no energy input from the cell
• Goes WITH the concentration gradient
• Usually small, uncharged particles

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ACTIVE TRANSPORT

• -requires energy input from the cell
• -goes against the concentration gradient
• -large particles or charged particles

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Types of Passive Transport

• Simple Diffusion
• Facilitated Diffusion

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SIMPLE DIFFUSION

• Molecules that can pass directly through the
  phospholipid layer of the cell membrane
• Gases
• Water (OSMOSIS)
• Small, uncharged particles

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FACILITATED DIFFUSION

• Molecules that need the assistance of a carrier
  protein to enter a cell.
• (large molecules)
• Glucose

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OSMOSIS- diffusion of water

• HYPERTONIC SOLUTION
• -low concentration of water
• -high concentration of solutes
• -water flows out of the cell
• PLASMOLYSIS- cell shrivels

• HYPOTONIC SOLUTION
• -high concentration of water
• -low concentration of solutes
• -water flows into the cell
• CYTOLYSIS- cell bursts

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ISOTONIC SOLUTION

• Balanced on both sides

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Things that affect the rate of diffusion

1. Temperature
2. Pressure
3. Size of molecules
4. Size of openings in the cell membrane

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Types of Active Transport

• 1 Solute Pumps- (charged items)
• 2 BULK TRANSPORT
• -EXOCYTOSIS
• -ENDOCYTOSIS
• PHAGOCYTOSIS
• PINOCYTOSIS

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SOLUTE PUMPS

• Amino acids, some sugars, and most ions are
  transported against the concentration gradient

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SODIUM-POTASSIUM ION PUMP(PAGE 70)

• Needed for the transmission of impulses by nerve
  cells.
• 3 Sodium ions are pumped out of the cell and 2
  Potassium ions are pumped in

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SODIUM-POTASSIUM ION PUMP(PAGE 70)

• STEP 1- 3 sodium ions attach to carrier protein
  which stimulates it to bind to Phosphate of ATP
• STEP 2- Binding of Phosphate causes the protein
  to change shape and expel the 3 sodium ions
  outside and collect 2 potassium ions

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SODIUM-POTASSIUM ION PUMP(PAGE 70)

• STEP 3- Loss of Phosphate causes the carrier
  protein to return to original shape and Potassium
  ions are released into the cell

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BULK TRANSPORT

• Way to get substances into or out of the cell
  that are too large for even a carrier protein
• EXOCYTOSIS- large items exiting the cell via a
  vesicle that fuses with the cell membrane
  (usually from the Golgi apparatus)- hormones,
  mucus, and cellular waste is secreted this way

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ENDOCYTOSIS

• large items entering the cell via a vesicle that
  is made by movement of the cell membrane
• PINOCYTOSIS- cell drinking
• PHAGOCYTOSIS- cell eating-

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PINOCYTOSIS- cell drinking

• When cell membrane comes in contact with
• liquid it folds in and forms a vesicle

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PHAGOCYTOSIS- cell eating- example is White Blood
Cell

• STEP 1- cell comes in contact with food particle
• STEP 2- cell membrane creates pseudopods that
  surround food
• STEP 3- vesicle is formed and food enters the cell

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RECEPTOR MEDIATED ENDOCYTOSIS- muscle cells

• Tiny receptors located on the cell membrane
• When a certain number of receptors is full then
  the cell goes through endocytosis