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Lysosomes
The cell’s recycling centers
Lysosome Structure
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Membrane-bound
Contains powerful digestive enzymes
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Size
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If membrane broke open, enzymes would destroy cell
0.05 to 0.5 micrometers in diameter
Proteins embedded in membrane
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protect activity of enzymes by regulating internal acidity
Transport digested materials away from lysosome
Lysosome Structure (cont.)
Lysosome Production
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Enzymes made in rough endoplasmic reticulum
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Enzymes delivered to Golgi apparatus via transport
vesicles
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Hydrolytic enzymes
Sacs formed by rough ER
Golgi apparatus processes enzymes
Lysosomes bud from Golgi apparatus w/ enzymes
inside
Lysosome Production (cont.)
Lysosome Function
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Newly formed lysosomes can perform one of three
tasks
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Endocytosis
Phagocytosis
Autophagocytosis
Endocytosis
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Endocytosis
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Cell membrane surrounds large nutritional molecule, forming
an endosome
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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
Endocytosis (cont.)
Phagocytosis
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Phagocytosis
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Cell membrane surrounds disease-causing bacteria or large
object, forming phagosome
Lysosome joins with phagosome, breaking down the object
or bacteria with enzymes
Phagocytosis (cont.)
Autophagocytosis
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Autophagocytosis
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ER wraps around spent cell structure, forming
autophagosome
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i.e. mitochondrion
Lysosome joins autophagosome, destroys structure, delivers
products to cytoplasm
Autophagocytosis (cont.)
Vacuoles
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Found within plant cells
Classified by some scientists as large lysosomes
Much larger than other lysosomes
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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
Vacuoles (cont.)