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Lysosomes PowerPoint Presentation

Lysosomes

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Lysosomes

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  1. Lysosomes The cell’s recycling centers

  2. LysosomeStructure • Membrane-bound • Contains powerful digestive enzymes • If membrane broke open, enzymes would destroy cell • Size • 0.05 to 0.5 micrometers in diameter • Proteins embedded in membrane • protect activity of enzymes by regulating internal acidity • Transport digested materials away from lysosome

  3. Lysosome Structure (cont.)

  4. Lysosome Production • Enzymes made in rough endoplasmic reticulum • Hydrolytic enzymes • Enzymes delivered to Golgi apparatus via transport vesicles • Sacs formed by rough ER • Golgi apparatus processes enzymes • Lysosomes bud from Golgi apparatus w/ enzymes inside

  5. Lysosome Production (cont.)

  6. Lysosome Function • Newly formed lysosomes can perform one of three tasks • Endocytosis • Phagocytosis • Autophagocytosis

  7. Endocytosis • Endocytosis • Cell membrane surrounds large nutritional molecule, forming an endosome • Complex lipids • Polysaccharides • Nucleic acids • Proteins • Lysosome fuses with endosome, delivering enzymes needed to break down molecules • Broken-down molecules delivered to cytoplasm by membrane proteins for later use

  8. Endocytosis (cont.)

  9. Phagocytosis • Phagocytosis • Cell membrane surrounds disease-causing bacteria or large object, forming phagosome • Lysosome joins with phagosome, breaking down the object or bacteria with enzymes

  10. Phagocytosis (cont.)

  11. Autophagocytosis • Autophagocytosis • ER wraps around spent cell structure, forming autophagosome • i.e. mitochondrion • Lysosome joins autophagosome, destroys structure, delivers products to cytoplasm

  12. Autophagocytosis (cont.)

  13. Vacuoles • Found within plant cells • Classified by some scientists as large lysosomes • Much larger than other lysosomes • 20 µm • Membrane-bound • Maintain turgor, or water pressure, inside cell to prevent wilting • Storage for nutrients, pigments, and harmful materials (opium, rubber) used to deter predators

  14. Vacuoles (cont.)