Biological membranes

• What model describes the structure of cell membranes?

  Fluid mosaic model
• What is the fluid mosaic model?

  Theory of membrane structure with proteins in phospholipids
• What is a glycoprotein?

  Protein with carbohydrate chain attached
• What is a glycolipid?

  Lipid with carbohydrate chain attached
• Why are cell membranes described as partially permeable barriers?

  They allow some molecules to pass through
• What does permeability refer to in cell membranes?

  Ability to let substances pass through
• How do some substances pass through cell membranes?

  By simple diffusion or protein channels
• What are carrier proteins used for in cell membranes?

  To transport specific molecules across membranes
• What determines the permeability of a cell membrane?

  The properties of the membrane's component molecules
• What are the roles of membranes at the surface of cells?

  • Surrounds cell components from the environment
  • Regulates transport of materials in and out
  • Contains antigens for immune recognition
  • Releases signaling chemicals for communication
• What are the roles of membranes within cells?

  • Separate organelle contents from cytoplasm
  • Form compartments for metabolic processes
  • Localize reactions in organelles like mitochondria
• What is the thickness range of a cell membrane?

  5 to 10 nm
• What is the glycocalyx?

  Layer of glycoproteins and glycolipids outside the membrane
• How do cell membranes differ in composition?

  • Differentiated cells have unique protein distributions
  • Long axon nerve cells have specific channels for ion transport
  • White blood cells have receptors for recognizing antigens
• What is the myelin sheath composed of?

  20% protein and 70% lipid
• What is the function of the myelin sheath in neurons?

  Insulates axons for efficient signal conduction
• How do the roles of proteins in cell membranes vary?

  They can act as channels, carriers, or receptors
• What is the significance of cholesterol in eukaryotic cell membranes?

  Regulates fluidity and mechanical stability
• What do antigens on cell membranes do?

  Help immune system recognize 'self' cells
• What happens to the structure of the fluid mosaic model?

  It can change shape and fluidity
• How do the functions of organelle membranes differ from plasma membranes?

  Organelle membranes form compartments for specific processes
• Cell Membrane Composition


  The mixture of molecules that make up the phospholipid bilayer of a cell membrane.
• Differentiated Cells


  Cells that have unique protein distributions, allowing them to perform specific functions.
• Axon Nerve Cells


  Cells with specific channels for ion transport, enabling electrical signaling.
• Muscle Fibers


  Cells with different protein distributions and channels that facilitate muscle contraction and relaxation.
• Protein Distribution


  The unique arrangement of proteins in a cell membrane, specific to its function and differentiation.
• Ion Transport


  The movement of ions across the cell membrane, crucial for electrical signaling and muscle function.