CELL MEMBRANE | Anatomy2Medicine
CELL MEMBRANE Strecture

CELL MEMBRANE

    • Membrane structure
      • Membranes are composed mainly of lipids and proteins
      • Membrane lipids
        • Phosphoglycerides are the major
        • sphingolipids
        • cholesterol
      • Phospholipids
        • form a bilayer,

 

  • hydrophilic head groups interact with water on both the extracellular and intracellular surfaces

 

        • hydrophobic fatty acyl chains in the central portion of the membrane.
      • Peripheral proteins are attached at the periphery of the membrane
      • Integral proteins span from one side of the membrane to the other.
      • Carbohydrates
        • attached to proteins and lipids on the exterior side of the cell membrane
        • They extend into the extracellular space.

 

  • Lipids and proteins

 

      • can diffuse laterally within the plane of the membrane.
      • Therefore, the membrane is termed ‘‘fluid mosaic.’’
  • Membrane function
    • Membranes serve as barriers that separate the contents of a cell from the external environment or the contents of individual organelles from the remainder of the cell.
    • The proteins in the cell membrane have many functions.
      • transport of substances across the membrane.
      • enzymes that catalyze biochemical reactions.
      • function as receptors that bind external ligands such as hormones or growth factors.
      • mediators that aid the ligand–receptor complex in triggering a sequence of events (e.g., G proteins) known as signal transduction;
        • second messengers (e.g., cAMP ) that alter metabolism are produced inside the cell.
  • cystic fibrosis transmembrane regulator (CFTR)
    • results in cystic fibrosis (CF)
    • a chloride ion channel found on cell membranes.
    • the most common mutation of which is the loss of a phenylalanine residue at position 508, known as the DF508 mutation