Cell Structure and Function

Cell Structure

Cell Membrane

• Also known as the plasma membrane
• Thin, semi-permeable layer that surrounds the cell
• Composed of:
  • Phospholipid bilayer (double layer of lipids)
  • Proteins (embedded or attached to the bilayer)
• Functions:
  • Regulates movement of substances in and out of the cell
  • Maintains cell shape and provides mechanical support
  • Acts as a barrier against external substances

Cytoplasm

• Gel-like substance inside the cell membrane
• Composed of:
  • Water (about 70-80%)
  • Salts
  • Sugars
  • Amino acids
  • Organelles (e.g., mitochondria, ribosomes)
• Functions:
  • Provides a medium for chemical reactions and metabolic processes
  • Supports the movement of organelles and cellular components
  • Helps maintain cell shape and provides mechanical support

Mitochondria

• Often referred to as the "powerhouses" of the cell
• Found in the cytoplasm, usually near the endoplasmic reticulum
• Functions:
  • Generate energy for the cell through cellular respiration (ATP production)
  • Regulate cell metabolism and energy production
  • Involved in cell signaling and apoptosis (programmed cell death)
• Structure:
  • Outer membrane
  • Inner membrane (folds into cristae to increase surface area)
  • Matrix (contains enzymes and other molecules involved in energy production)