Cell Biology Lecture 3

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  • 1. Advanced Cell Biology 2014 1nd Semester Department of Animal Science Chungbuk National University 4nd Lecture
  • 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. 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. Development of Ideas about Membrane Structure
  • 5. “ Fluid Mosaic Model” of biological Membrane
  • 6. Lipids : Framework of biological membrane Hydrophilic (Water lovers ) Hydrophobic (Water haters) Phosphoglycerides
  • 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. Sphingolipid : N-containing charge head
  • 9. Cholresterol is the essential component of biological membrane Cholresterol give ‘rigidity’ in membrane, therefore help to maintain integrity
  • 10. Lipid rafts Sphingolipids and cholestrol form small islands (50nm) Involved in signalings
  • 11. Integral Membrane Proteins
  • 12. Transmembrane segment - Mostly alpha-Helix - Hydrophobics
  • 13. Hydrophaty Plots Plot based on the hydrophobility of amino acids in a protein
  • 14. C-terminal isoprenoid N-terminal myristoyl tail
  • 15. Membrane Potential (Ion-gradient as energy)
  • 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. Light-driven Proton Pump : Bacteriorodopsin Convert Light energy as chemical energy (Formation of proton gradients)
  • 18. Mitocondrial F1 ATPase (ATP Synthase)
  • 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. 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. - 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. Channels Channel : integral membrane proteins with transmembrane pores that allow particular ions or small molecules
  • 23. Selectivity filter of Ion Channel Potassium (K+) channel should allow pass-through of Potassium, but Sodium
  • 24. Voltage-gated K+ Channel - voltage-gated K+ and Na+ channels produce action potentials in excitable cells
  • 25. Nature 2013EM reconstitution of TRPV1
  • 26. Ion Channel Gated by Extracellular Ligands Glutamate Receptor
  • 27. Aquaporin (Water Channel)
  • 28. Xenopus oocyte injected by Aquaporin cRNA
  • 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. Epithelial Transport