Cell Biology Lecture 3


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Cell Biology Lecture 3

  1. 1. Advanced Cell Biology 2014 1nd Semester Department of Animal Science Chungbuk National University 4nd Lecture
  2. 2. 1st week : Introduction 3rd week :Research Strategies For Cell Biology 5nd week : Nucleus, Transcription and Splicing 7nd week : Membrane and Channel 9nd week : Membrane Trafficking 11nd week : Cell Signaling 13nd week : Cytoskeleton 15nd week : Cell Cycle
  3. 3. Membrane - Barrier between each cell and its environment - Partition of the cytoplasm into compartments * Nucleus * organelles - All biological membranes have much in common • Fluid bilayer of lipid molecules • Integral membrane proteins • Pheripheral membrane proteins
  4. 4. Development of Ideas about Membrane Structure
  5. 5. “ Fluid Mosaic Model” of biological Membrane
  6. 6. Lipids : Framework of biological membrane Hydrophilic (Water lovers ) Hydrophobic (Water haters) Phosphoglycerides
  7. 7. • Main lipid constitutes of membranes • Glycerol + two fatty acids + phosphoric acids + alchohol • Depend on alcohols esterified to the phosphates - Phosphatidic acid [PA] - Phosphatidylglycerol [PG] - Phosphatidiylethanolamine [PE] - Phosphatidylcholine [PC] - Phosphatidylserine [PS] - Phophatidylinositol [PI]
  8. 8. Sphingolipid : N-containing charge head
  9. 9. Cholresterol is the essential component of biological membrane Cholresterol give ‘rigidity’ in membrane, therefore help to maintain integrity
  10. 10. Lipid rafts Sphingolipids and cholestrol form small islands (50nm) Involved in signalings
  11. 11. Integral Membrane Proteins
  12. 12. Transmembrane segment - Mostly alpha-Helix - Hydrophobics
  13. 13. Hydrophaty Plots Plot based on the hydrophobility of amino acids in a protein
  14. 14. C-terminal isoprenoid N-terminal myristoyl tail
  15. 15. Membrane Potential (Ion-gradient as energy)
  16. 16. Pump : enzymes that utilize energy from ATP or light or other sources to movie ions and other solutes across membranes - Formation of gradients expense of chemical energy - Convert chemical energy to electric energy Carrier : enzyme-like proteins provide passive pathway for solute to move across membranes - From higher concentration and lower concentration - Carriers uses ion gradient as a source of energy Channel : ion-specific pores which can open and close transiently - Channel open : ion passes quickly across membrane - Channel close : stop - Movement of ions through channel is basis of control of electric potential across mebrane
  17. 17. Light-driven Proton Pump : Bacteriorodopsin Convert Light energy as chemical energy (Formation of proton gradients)
  18. 18. Mitocondrial F1 ATPase (ATP Synthase)
  19. 19. P-Type Cation Pumps : Ca2+-ATPase (SERCA1) Ca2+ acts as important second messenger in cells Therefore, Ca2+ concentrations should be Pumps Ca2+ out of cytoplasm into the endoplasmic reticulum
  20. 20. Carrier : enzyme-like proteins provide passive pathway for solute to move across membranes - From higher concentration and lower concentration - Carriers uses ion gradient as a source of energy
  21. 21. - Uniproters GLUT carrier for glucose - Antiporters Driving ion moves in one direction, then drive substrate in the others - Symporters ion and substrates goes to the same directions
  22. 22. Channels Channel : integral membrane proteins with transmembrane pores that allow particular ions or small molecules
  23. 23. Selectivity filter of Ion Channel Potassium (K+) channel should allow pass-through of Potassium, but Sodium
  24. 24. Voltage-gated K+ Channel - voltage-gated K+ and Na+ channels produce action potentials in excitable cells
  25. 25. Nature 2013EM reconstitution of TRPV1
  26. 26. Ion Channel Gated by Extracellular Ligands Glutamate Receptor
  27. 27. Aquaporin (Water Channel)
  28. 28. Xenopus oocyte injected by Aquaporin cRNA
  29. 29. Cooperation of Channel, Pump and Carrier in Cell 1. Chemical Energy from ATP was converted as concentration gradients of C+ 2. Carrier uses electrochemical gradient of C+ to drive transport C+ and S
  30. 30. Epithelial Transport