Generally attached to proteins on the outer membrane layer On the inner or outer surface of the phospholipid bilayer not embedded within the phospholipidsĬarbohydrates (components of glycoproteins and glycolipids) May or may not penetrate through both layers Integral Proteins (for example, integrins)Įmbedded within the phospholipid layer(s). The Components and Functions of the Plasma MembraneĪttached between phospholipids and between the two phospholipid layers The mitochondrial inner membrane contains 76% protein and 24% lipid. For example, myelin contains 18% protein and 76% lipid. The proportions of proteins, lipids, and carbohydrates in the plasma membrane vary with cell type. For comparison, human red blood cells, visible via light microscopy, are approximately 8 µm wide, or approximately 1,000 times wider than a plasma membrane. Plasma membranes range from 5 to 10 nm in thickness. The fluid mosaic model describes the structure of the plasma membrane as a mosaic of components – including phospholipids, cholesterol, proteins, and carbohydrates – that gives the membrane a fluid character. The model has evolved somewhat over time, but it still best accounts for the structure and functions of the plasma membrane as we now understand them. Nicolson in 1972 to explain the structure of the plasma membrane. The fluid mosaic model was first proposed by S.J.
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