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Lysosomes. The cell’s recycling centers. Lysosome Structure. 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
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Lysosomes The cell’s recycling centers
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
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
Lysosome Function • Newly formed lysosomes can perform one of three tasks • Endocytosis • Phagocytosis • Autophagocytosis
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
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
Autophagocytosis • Autophagocytosis • ER wraps around spent cell structure, forming autophagosome • i.e. mitochondrion • Lysosome joins autophagosome, destroys structure, delivers products to cytoplasm
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