Cell Transportation

[ ] =  concentration 

Low to high: requires energy 

High to low:  doesn’t require energy. 

Passive transport: movement of molecules from a high concentration to low concentration, No energy required

Ex.  

• Simple diffusion
  • Moving molecules through the bilayer from high to low concentration
  • [H] -> [L] works without molecules that are very small
  • No charge: non-polar molecules, to travel through bi-layer
• Facilitated diffusion
  • “Easy diffusion” using protein channels
• Osmosis
  • When H2O moves from an [H]--> [E]

Factors that effect the speed of passive transport: 

• Size of molecule
• Concentration gradient
  • : 2 different solutions w/ different concentrations separated by a membrane
• Presence of channels
• Temperature
• Thickness of membrane

Passive transport leads to an equilibrium. +

Active Transport:  movement of molecules from a low concentration to high concentration, energy required

vesicles: cell membrane “bag” used in bulk active transport

Ex. 

• Ion pumps
• Endocytosis w/ vesicles
• Exocytosis w/ vesicles

Tonicity: describes a solution where water is  the solvent

Solution =  solvent + solute

Hypertonic: more solute

Hypo: less solute 

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