Lysosomes, Vacuoles and Microbodies

Lysosomes

• Structure - spheres arising as buds from Golgi body.
• Lysosome Functions
  • main organelle of digestion.
  • provides safe place for digestion.
  • contains in excess of 40 enzymes for every class of macromolecule.
  • participates in programmed cell destruction (ex: tadpole tails, human embryo finger webs).

Vacuoles

• Structure
  • a membrane- enclosed space.
  • vesicles are smaller than vacuoles.
• Various functions in plants and animals.
• Animal functions:
  • food vacuoles
  • contractile vacuoles expel excess water from freshwater protists.
• Plant functions:
  • storage - proteins in seeds, toxic metabolic wastes, pigments (flowers).
  • acts as lysosome.
  • stores water to assist growth.
  • increases surface area to volume ratio of large plant cells.

Microbodies

• Group of structures that are not really cytomembrane organelles.
• Peroxisomes
  • structure - single membrane that arises from cytosol components.
  • function - metabolic compartment for breaks down of various macromolecules.
  • very destructive hydrogen peroxide (H₂O₂) byproduct is reduced to water with a catalase.
  • liver cell peroxisomes break down alcohol.
• Glyoxysome - in lipid-rich seeds, breaks down lipids into sugars.