STPM Form 6 Biology - ER, Golgi Apparatus, Lysosome


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STPM Form 6 Biology - ER, Golgi Apparatus, Lysosome

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STPM Form 6 Biology - ER, Golgi Apparatus, Lysosome

  1. 1. EndoplasmicRecticulum & GolgiApparatus
  2. 2. Nucleus & ER
  3. 3. Rough ER Ribosomes synthesize excreted proteins  Stored in cisternae or vesicle Modify proteins  Glycosylation of proteins Delivery of membrane associated proteins Often interacts with the Golgi Salivary glands & Pancreas
  4. 4. Rough Endoplasmic ReticulumFunctions: starting point of BIOSYNTHETIC PATHWAYSynthesis of:• proteins• carbohydrate chains• phospholipidsPROTEINMODIFICATION
  5. 5. Membrane Factory
  6. 6. Rough ER vs Smooth ER
  7. 7. Smooth ER Storage and metabolism of carbohydrates Detoxification reactions in liver Synthesis and Transport of Lipids
  8. 8. Synthesis of steroid hormones Endocrine cells  gonad  adrenal cortex
  9. 9. Glucose release from liver Gluconeogenesis Glycogen become glucose
  10. 10. Sarcoplasmic recticulum  Muscle cell  Storage and release Calcium ions
  12. 12. Most commonly found in
  13. 13. ER and Golgi  Often adjacent in cytoplasm of cell  Both are membrane producers  Membrane has sides  Vesicles are produced inside out  Vesicle fuses with surface and excreted proteins are released and integral proteins are added along with membrane  ER often performs first steps of modification that is later finished in Golgi
  14. 14. Golgi apparatus Complex collection of membrane Has polarity  Cis and trans surfaces Responsible for secretion  Very prominent in cells that serve secretory functions-such as epithelial cells Modifies structures previously synthesized in the ER
  15. 15. Cytoplasmic membranes-1 movement of molecules (proteins, lipids,neurotransmitters) from donor to acceptor compartment –
  16. 16. Golgi Function Cis face is nearer the center of cell  Cis face is often adjacent to ER Trans face is nearer the cell membrane Activity is directional  Starts at cis face and moves to trans
  17. 17. Fig. 6-13 cis face (“receiving” side of 0.1 µm Golgi apparatus) Cisternae trans face (“shipping” side of TEM of Golgi apparatus Golgi apparatus)
  18. 18. ER and Golgi  Synthesis in ER but modification in Golgi  Modification of sugar groups in enzymes  Each cisternae contains different enzymes
  19. 19. Examples of Golgi Function Replace sugars placed on glycoproteins Modification of phospholipid acylgroups and head groups Molecule targeting and assembly Production of vesicles to delivery membrane associated molecules and excreted molecules to cell surface
  20. 20. Importance of Golgi The Golgi Body interacts mostly with the Endoplasmic Reticulum, plasma membrane, and lysosomes of the cell. Glycosylation in the Golgi Apparatus is the mechanism that directs certain proteins to their proper cellular locations. Without the Golgi body the cell would die, because it wouldn’t be able to create lysosomes which break down food for the cell. Also, proteins wouldn’t go where they need to (lacking the transport modification).
  21. 21. Cell Wall Formation
  22. 22. Cell Renewal Cells and their molecules age and become less effective An important cellular function is renewal  Old molecules and organelles are recycled  New phospholipids are produced for the membrane  Toxic molecules need to be collected and detoxified Sometimes a cell needs to commit suicide  Called autolysis or apoptosis
  23. 23. Vesicle OrganellesPerform many of the renewal functions Lysosome Peroxisome Glyoxisome
  24. 24. Lysosome Contains digestive enzymes used to degrade macromolecules or organelles Originates in ER but enzymes are activated in Golgi  ER produce enzymes and membranes  Golgi modifies and activates enzymes Important in macrophages for degradation of particles acquired via phagocytosis Used to degrade organelles- autophagy
  25. 25. Nucleus 1 µmIntracellular digestionpH 4-5RNAaseDNAaseProteaseCarbohydrase Lysosome DigestiveLipase enzymesPhosphatase Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis
  26. 26. Vesicle containing 1 µm two damaged organellesAutophagyOld and wornout organellescan berecycled Mitochondrion fragment Peroxisome fragment Lysosome Peroxisome Mitochondrion Digestion Vesicle (b) Autophagy
  27. 27. Cell Death Sometimes used in development of organism  Hand development  Certain cells are programmed to die at appropriate times Defense against viral or intracellular bacterial infections  Self-destruct  Program is started by T cells Apoptosis is often accomplished by leaky or popping lysosomes
  28. 28. Peroxisomes Acts as detoxifying agent Convert toxic hydrogen peroxide to water Peroxisomes are formed by aggregation of lipids and proteins (not formed in ER) Self-replicate using cytosol protein Many are found in liver cells  Degrade alcohols into peroxide then into water and oxygen
  29. 29. Peroxisome Also responsible for degradation of fatty acids in cytosol Modify fatty acids and phospholipids and incorporate into peroxisome membrane
  30. 30. Glyoxysomes Specialized peroxisomes found in plant seeds Recognize appropriate signals and begin to degrade stored fat in seed Fat is converted to sugars which allows seedling to sprout Once photosynthesis starts, glyoxysomes degrade