Cell Membrane, vacuoles, vesicles and lysosomes

Cell membrane  The “skin” of the cell that controls what goes in and out of the cell  Made up of a bi-layer of phospholipids  Other molecules (proteins and carbohydrates) impeded in the bi-layer  Cell has to be small so that the volume does not out grow the surface area

Vacuoles  Used in cell maintenance Food vacuoles  Formed by phagocytosis  Collects food from outside Contractual vacuole  Pumps out excess water Central vacuole  Hold materials (waste, access food, harmful materials)

Vesicles  Sacs made of membrane inside of a cell  Transport products in various stages of processing from one cisterna to an other Transport vesicle  Tiny membrane sacs in a cell’s cytoplasm carrying molecules produced by the cell

Lysosomes  Membrane-bound sac of hydrolytic enzymes that the cell uses to digest macromolecules  Found in the cytoplasm of eukaryotic cells  Lysosomal enzymes can hydrolyze proteins, polysaccharides, fats, and nucleic acids  Carry out intracellular digestion by a process called phagocytosis  Lysosomes also use hydrolytic enzymes to recycle the cell’s own organic material in a process called autophagy  Lysosomes provide a space where the cell can digest macromolecules safely  Formed by budding off the Golgi membrane

Transport vesicles containing inactive hydrolytic enzymes buds off the ER membrane Golgi apparatus activates hydrolytic enzymes Lysosomes containing active hydrolytic enzymes bud off the Golgi membrane Autophagy: a lysosome engulfs a damaged organelle Phagocytosis: a food vacuole pinches off the plasma membrane, enclosing food particle Food vacuole fuses with lysosome Hydrolytic enzymes digest particles engulfed by lysosomes ;breakdown products (monomers) pass across lysosome membrane into cytosol