Passive and Active transport in Cell membrane

• Passive transport


  Transport of substances that do not require expenditure of energy.
• Active transport

  Transport of substances that require the expenditure of energy
• Types of Diffusion

  1. Simple Diffusion
  2. Facilitated Diffusion (Carrier Mediated & Channel-Mediated)
• Simple Diffusion


  Transport of molecules without assistance (small uncharged molecules or non-polar molecules)
• Carrier-Mediated Facilitated Diffusion


  Transport of polar, larger, or charged molecules in-and-out of the cell membrane through carrier proteins.
• Channel-Mediated Facilitated Diffusion


  Protein Channels in the cell membrane allow inorganic ions to pass through.
• Channel-Mediated Facilitated Diffusion



  Protein Channels in the cell membrane allow inorganic ions to pass through.

  
• Diffusion

  Movement of particles from an area of high concentration to low concentration
• Factors affecting diffusion rate

  1. Concentration gradient
  2. Distance
  3. Surface area
  4. Temperature
  5. Thickness of barriers
• Osmosis 


  Diffusion of water molecules from an area of high solute concentration to low solute concentration across a semi-permeable membrane
• Hypertonic: Higher concentration of solute in extracellular fluid
• Hypotonic: Lower concentration of solute in extracellular fluid
• Isotonic: Equal concentrations of solute in intra- and extracellular fluid
• Tonicity: Osmotic pressure of solution
• Plant cell, hypotonic solution, turgid
• Animal cell, hypertonic, shriveled
• Plant cell, isotonic, flaccid
• Active transport transports molecules against the concentration gradient
• Passive transport transports molecules down the concentration gradient
• Types of active transport:

  1. Simple transport
  2. Counter transport
  3. Cotransport
• Simple transport is the movement of molecules from a region of high concentration to a region of low concentration without assistance of protein channels (protein pump)
• Counter transport is the movement of molecules through the use of integral proteins where one travels into the cell membrane and one travels out. (sodium potassium pump)
• Cotransport is when glucose relies on the concentration gradient of sodium ions to move into the cell against its concentration gradient (sodium-glucose symport/antiport)
• Ways of transporting larger molecules:

  1. Endocytosis
  2. Exocytosis
• Endocytosis is the entry of larger molecules into the cell by the process of pinocytosis or phagocytosis
• Exocytosis is the exit of large molecules from the cell through the use of vesicles (Integral proteins) fusing with the cell membrane
• Pinocytosis is the entry of extra-cellular fluid that carries larger molecules into the cell
• Phagocytosis is the entry of large molecules through the engulfment of them.
• Types of solutions:

  1. Hypertonic
  2. Isotonic
  3. Hypotonic

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