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Structure of the Cell > Plasma Membrane / Cell Membrane

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Estimated time: 3 minutes
  • Key Points: Cell Membrane
CBSE: Class 12
CISCE: Class 10

Key Points: Cell Membrane

  • The cell membrane (plasma membrane) is a thin, flexible, living outer boundary that separates the cell from the external environment.
  • It is mainly composed of lipids and proteins, with phospholipids arranged in a bilayer (hydrophilic heads outward and hydrophobic tails inward).
  • The membrane also contains cholesterol and carbohydrates, and the protein–lipid ratio varies in different cells (e.g., RBC membrane has ~52% protein and ~40% lipids).
  • According to the Fluid Mosaic Model (Singer and Nicolson, 1972), the membrane is dynamic, with proteins moving within the lipid bilayer.
  • Membrane proteins are of two types: integral proteins (embedded in the membrane) and peripheral proteins (present on the surface).
  • The cell membrane is selectively permeable, allowing certain substances to pass while restricting others.
  • It regulates the movement of ions and molecules, maintains cell shape, and helps in communication between the cell and its environment.

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Shaalaa.com | Cell Unit of Life part 7 (Structure of cell: Plasma membrane, diffusion)

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Cell Unit of Life part 7 (Structure of cell: Plasma membrane, diffusion) [00:12:21]
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