Endomembrane System - PowerPoint PPT Presentation

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Endomembrane System

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  1. Endomembrane System By Mariah Ghant, Saori Ishizuka, and Monica Lin

  2. Definition • The set of membranes found in eukaryotic cells that carry out a variety of tasks in the cell • Tasks include: • Synthesis of proteins • Protein transport • into membranes and organelles • out of the cell • Metabolism and movement of lipids • Detoxification of poisons

  3. Major Parts of the Endomembrane • Nuclear Envelope • Endoplasmic Reticulum (Smooth and Rough) • Golgi Apparatus • Lysosomes • Vacuoles • Plasma Membrane

  4. Nuclear Envelope Structure Function Encloses the nucleus Separates its contents from the cytoplasm • Double Membrane • Perforated by pore structures • Nuclear side is lined with nuclear lamina • Ribosomes on cytoplasmic side

  5. Endoplasmic Reticulum Rough ER • Makes secretory proteins (glycoproteins) • Keeps proteins seperated • Makes transport vesicles • “Membrane Factory” for the cells • Many proteins and phospholipids added to its own membrane • Has ribosomes • continuous with smooth ER Function Structure

  6. Endoplasmic Reticulum Smooth ER • Lacks ribosomes • Membranes system of interconnected tubules Function Structure Synthesis of Lipids Metabolism of Carbohydrates Detoxification of Drugs and Poisons Stores calcium ions

  7. Golgi Apparatus Functions Structure Consists of flattened membranous sacs (citernae) • Multiple interactions with the product of the ER (proteins): • Modifies • Stores • Sends to multiple destinations • 2 poles of Golgi stack: • Cis face- receives vesicles containing ER products • trans face- dispatches vesicles

  8. Lysosomes Functions Structure Membranous sac of hydrolytic enzymes • Used in animal cells to digest macromolecules • Autophagy- process of recycling the cell’s own organic material • Phagocytosis- process of intracellular digestion in amoebas and small organisms

  9. Vacuoles Functions Structure Membrane-bounded vesicles Container shape Contains pigments that color cells • Their functions vary in different cells: • Food Vacuoles- fuses with the lysosome during the process of phagocytosis • Contractile Vacuoles- pump excess water out of the cell • Central Vacuole- located in mature plant cells; holds important organic compound reserves; main repository of inorganic ions • Major role in the growth of plants

  10. Plasma Membrane Functions Structure Thin layer of cytosol between central vacuole and plasma membrane • Encloses the entire cell • Protein secretion occurs here after they’ve been carried by transport vesicles

  11. Interactions • The endomembrane interacts with the nucleus via nuclear envelope • The nuclear envelope is connected to the rough ER, which encloses the nucleus

  12. Review • Nuclear envelope is connected to rough ER • Membranes and proteins produced by the ER flow in the form of transport vesicles to the Golgi • Golgi pinches off transport vesicles and other vesicles that give rise to: • lysosomes • other types of specialized vesicles • vacuoles • Lysosome is then available for fusion with another vesicle for digestion • Transport vesicle carries proteins to plasma membrane for secretion • Plasma membrane expands by fusion of vesicles; proteins are secreted from the cell

  13. Video http://www.youtube.com/watch?v=PASnAaulK-Y