Cell Membranes

• The Fluid Mosaic Model is a model of the cell membrane that describes the structure of the membrane as a series of fluid-filled compartments
• Cell Membranes contain:

  • Phospholipids
  • Proteins
  • Glycoproteins
  • Glycolipids
  • Cholesterol
• Phospholipids are arranged as a phospholipid bilayer, creating a partially permeable membranes
• Hydrophillic heads on Phospholipids are attracted to water due to the negative charge
• Cholesterol restricts lateral movement, making membranes less fluid at higher temperatures preventing water and dissolved ions from leaking
• Peripheral Proteins do not extend across a cell membrane, they act as receptors on the membrane
• Integral Proteins span the membrane acting as protein carriers or channel proteins involved in transport
• Protein Channels fill with water for soluble ions to diffuse through
• Protein Carriers bind to larger molecules e.g. glucose, change shape, and transport through the membrane
• Membranes are partially permeable, allowing substances to pass through them e.g. O2, CO2, H2O