Plasma Membrane

• Fluid Mosaic Model


  Refers to the the fluidity of the phospholipid bilayer with embedded proteins giving it a mosaic appearance.
• Hypertonic


  When the extracellular environment has a higher solute concentration than the cell.
• Hypotonic


  When the extracellular environment has a lower solute concentration than the cell.
• Isotonic


  When both the cell and the extracellular environment has equal solute concentration.
• Plasma Membrane


  Controls what goes in and out of the cell as it is selectively permeable and maintains homeostasis.
• Passive transport


  The movement of molecules from high to low concentration, following the concentration gradient without the use of energy.
• Active Transport


  Movement of molecules from low to high concentration, against the concentration gradient with the use of energy in the form of ATP and embedded proteins such as carrier proteins. Occurs when molecules are large, polar and/or charged.

  • E.g. Sodium-potassium pump, proteins
• Endocytosis


  Bulk movement of molecules into a cell by engulfment as it fuses with the plasma membrane to form a vesicle around it.
• Exocytosis


  Bulk movement of materials out of the cells as vesicles fuse with the plasma membrane, pushing the molecules out.
• Diffusion


  Movement of molecules from high to low concentration across the phospholipid bilayer. Molecules must be small, non-polar and uncharged in order to pass through the membrane easily.

  • E.g. Water, Oxygen
• Facilitated Diffusion


  Movement of molecules from high to low concentration through the use of embedded proteins such as channel or carrier proteins as they may be, charged or polar.

  • E.g. Glucose, amino acids
• TRACIE - Proteins in the Plasma Membrane

  T - Transport

  R - Receptor

  A - Anchorage

  C - Cell Identity

  I - Intracellular Joining

  E - Enzymes
• Labelling the Plasma Membrane

  A) Phospholipid

  B) Peripheral Protein

  C) Channel Protein

  D) Carrier Protein

  E) Glycoprotein

  F) Integral Proteins

  G) Cholesterol

  H) Phosphate Head

  I) Fatty Acid Tail

  J) polar/hydrophilic

  K) non-polar/hydrophobic

  
• Phagocytosis


  Engulfment of solids into the cell.
• Pinocytosis

  Engulfment of liquids into the cell.
• Osmosis


  Movement of water molecules from low to high solute concentration.
• Turgid


  When a plant cell becomes hypotonic, it swells up but does not burst due to presence of the cell wall.
• Lysis


  When an animal cell becomes hypotonic and bursts.
• Plasmolysis


  When a plant cell becomes hypertonic and its cell membrane shrinks away from the cell wall.
• Crenation


  When an animal cell becomes hypertonic and shrinks.
• Cholesterol


  Maintains the fluidity and stability of the plasma membrane.
• Glycolipid


  Carbohydrate chains attached to the phospholipids in the plasma membrane and is involved in cell recognition.
• Hydrophilic


  Water loving
• Hydrophobic


  Water repelling.