LysosomesLysosomes

The cell’s recycling centersThe cell’s recycling centers

LysosomeLysosomeStructureStructure Membrane-boundMembrane-bound Contains powerful digestive enzymesContains powerful digestive enzymes

If membrane broke open, enzymes would destroy cellIf membrane broke open, enzymes would destroy cell SizeSize

0.05 to 0.5 micrometers in diameter0.05 to 0.5 micrometers in diameter Proteins embedded in membrane Proteins embedded in membrane

protect activity of enzymes by regulating internal acidityprotect activity of enzymes by regulating internal acidity Transport digested materials away from lysosomeTransport digested materials away from lysosome

Lysosome Structure (cont.)Lysosome Structure (cont.)

Lysosome ProductionLysosome Production

Enzymes made in rough endoplasmic Enzymes made in rough endoplasmic reticulumreticulum Hydrolytic enzymesHydrolytic enzymes

Enzymes delivered to Golgi apparatus via Enzymes delivered to Golgi apparatus via transport vesiclestransport vesicles Sacs formed by rough ERSacs formed by rough ER

Golgi apparatus processes enzymesGolgi apparatus processes enzymes Lysosomes bud from Golgi apparatus w/ Lysosomes bud from Golgi apparatus w/

enzymes insideenzymes inside

Lysosome Production (cont.)Lysosome Production (cont.)

Lysosome FunctionLysosome Function

Newly formed lysosomes can perform one Newly formed lysosomes can perform one of three tasksof three tasks EndocytosisEndocytosis PhagocytosisPhagocytosis AutophagocytosisAutophagocytosis

EndocytosisEndocytosis EndocytosisEndocytosis

Cell membrane surrounds large nutritional Cell membrane surrounds large nutritional molecule, forming an endosomemolecule, forming an endosome

Complex lipidsComplex lipids PolysaccharidesPolysaccharides Nucleic acidsNucleic acids ProteinsProteins

Lysosome fuses with endosome, delivering Lysosome fuses with endosome, delivering enzymes needed to break down moleculesenzymes needed to break down molecules

Broken-down molecules delivered to Broken-down molecules delivered to cytoplasm by membrane proteins for later usecytoplasm by membrane proteins for later use

Endocytosis (cont.)Endocytosis (cont.)

PhagocytosisPhagocytosis

PhagocytosisPhagocytosis Cell membrane surrounds disease-causing Cell membrane surrounds disease-causing

bacteria or large object, forming phagosomebacteria or large object, forming phagosome Lysosome joins with phagosome, breaking Lysosome joins with phagosome, breaking

down the object or bacteria with enzymesdown the object or bacteria with enzymes

Phagocytosis (cont.)Phagocytosis (cont.)

AutophagocytosisAutophagocytosis

AutophagocytosisAutophagocytosis ER wraps around spent cell structure, forming ER wraps around spent cell structure, forming

autophagosomeautophagosome i.e. mitochondrioni.e. mitochondrion

Lysosome joins autophagosome, destroys Lysosome joins autophagosome, destroys structure, delivers products to cytoplasmstructure, delivers products to cytoplasm

Autophagocytosis (cont.)Autophagocytosis (cont.)

VacuolesVacuoles

Found within plant cellsFound within plant cells Classified by some scientists as large lysosomesClassified by some scientists as large lysosomes Much larger than other lysosomesMuch larger than other lysosomes

20 µm20 µm Membrane-boundMembrane-bound Maintain Maintain turgorturgor, or water pressure, inside cell , or water pressure, inside cell

to prevent wiltingto prevent wilting Storage for nutrients, pigments, and harmful Storage for nutrients, pigments, and harmful

materials (opium, rubber) used to deter materials (opium, rubber) used to deter predators predators

Vacuoles (cont.)Vacuoles (cont.)