L03 organeles


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L03 organeles

  1. 1. Intracellular organelles and molecular mechanisms of organi z ation of a eucar y otic cell
  2. 2. T ypical organelles in eucaryotic cells
  3. 3. Membrane-bounded compartments <ul><li>Nucleus </li></ul><ul><li>Endoplasmic reticulum </li></ul><ul><li>Golgi apparatus </li></ul><ul><li>Lysosomes </li></ul><ul><li>Endosomes </li></ul><ul><li>Mitochondria </li></ul><ul><li>Chloroplasts </li></ul><ul><li>Peroxisomes </li></ul><ul><li>Advantages of compartments: </li></ul><ul><li>Microenvironment for enzymes, cofactors and substrates </li></ul><ul><li>More efficient course of chemical reaction due to a reduced diffusion of molecules </li></ul><ul><li>Appropriate ionic milieu (pH, redox potential etc) </li></ul><ul><li>Separation of dangerous activities (proteolytic enzymes oxidative enzymes etc) </li></ul>
  4. 4. How to study organelles: optical and electron microscopy Saccharomyces cerevisiae. Cell size : 3-5 µ m Phase contrast microscope ELM – freeze -fracturing ELM - u ltrathin section
  5. 5. How to study of organelles: differential centrifugation
  6. 6. How to study of organelles: gradient centrifugation
  7. 7. Nucleus Jaderný obal Jadérko Chromatin Nuclear envelope Nucleus
  8. 8. Mitochondria C ompartment s: Outer membrane Matrix Intermembranous space Fluorescing mitochondria Mitochondria – ultrathin section
  9. 9. Chloroplasts Light microscope E lectron microscope Flattened membrane vesicles acumulating to form grana grana
  10. 10. Endoplasmic reticulum flattened membrane cisternae rough ER – cisternal surface covered by ribosomes smooth ER cisternal surface without ribosomes Function: rER- s y nthesis of proteins for secretory pathway sER – synthesis of lipids and steroids
  11. 11. Golgi ap p ar a t us stacks of flattened cisternae with perifer al vesicles Synthesis and packaging of molecules destined to be secreted from the cell
  12. 12. Vesicular transport : secretory vesicles (dark blue) and endosomes (light blue)
  13. 13. Peroxisomes small membrane-bounded vesicles that provide containers for reactions where a dangerously reactive hydrogen peroxide is generated and degraded.
  14. 14. Arrangement of organelles in a liver cell (multipolar) and in a pancreatic cell (polar orientation) Multipolar organization Polar organization
  15. 15. Cytoskeleton as a scaffoulding for cell organelles Actin Microtubules Intermediate filaments
  16. 16. Topology of organelles in a typical eucaryotic cell: A cytoskeleton – a system of protein filaments (microtubules,actin filaments and intermediate filaments) crisscrossing the cytoplasm and forming with other proteins a scaffolding for membrane organelles
  17. 17. The placement of organelles by microtubules green- MT blue – ER, yellow - GA MT ER MT GA
  18. 18. Amino acid sequences as signals for r ecognition or attachment
  19. 19. Attachment of melanosomes to MT, actin filaments and PM Attachment of vaculoles to actin cables via signal proteins and adaptors
  20. 20. Microtubule-based transport and intra-cellular trafficking pathways . Many intracellular trafficking pathways involve active and directed transport along the microtubule cytoskeleton. Microtubule-dependent trafficking in mammalian cells includes: (a,b,c) ER-to-Golgi transport, (d) TGN-to-ER transport and (e) lysosomal, (f,g) endosomal and (h) mitochondrial motility
  21. 21. Plectin molecules serve as linkers between intermediate filaments (orange), microtubules (red) and actin filaments (yellow)
  22. 22. Key terms from the lecture 1. Size of cells and organelles 2. Overview of eucaryotic cell organelles 3.Techniques of organelle separation and description (microscopy, gradient centrifugation, differential centrifugation 4. Organelle description: nucleus, mitochondria, chloroplasts, ER, GA, secretory vesicles, lysosomes, peroxisomes 5. Cytoskeletal components and localization of organelles 6. How to prove co-localization of ER or GA with the microtubules