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Lecture 2 Monday, January 26, 2004

Lecture 2 Monday, January 26, 2004. Survey Introduction continued :CSK, tensegrity. Basic cellular components. Geodesic- Buckminster Fuller.

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Lecture 2 Monday, January 26, 2004

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  1. Lecture 2Monday, January 26, 2004 • Survey • Introduction continued :CSK, tensegrity. • Basic cellular components

  2. Geodesic- Buckminster Fuller A geodesic dome uses a pattern of self-bracing triangles in a pattern that gives maximum structural advantage, thus theoretically using the least material possible. (A "geodesic" line on a sphere is the shortest distance between any two points.)

  3. Nucleus connected to the CSK, modeled with straws.

  4. Tensegrity

  5. How does the CSK provide structure? Signals travel at speed of sound, as expected for a tensegrity model. Some results are not compatible with tensegrity model With or without microtubules

  6. Percolation: an alternate theory

  7. Malines, Belgium Fibroblast

  8. Pulling out the chromosomes A micropipet can suck up the end of a chromosome and then the entire 23 Can be pulled out, indicating they are all connected.

  9. Cells incorporate into Nano-fabricated devices Attaching to needles Stretching on a cantilever Growing on electrodes

  10. The generic cell Basic structure And components

  11. Building blocks • Water • Cl, Na, K, Ca, Mg (50) - Electrolytes • Fatty acids-lipids- (200) Phospholipids • Amino Acids- (115) Proteins • Sugars- (100) Carbohydrates • Sugars + Bases (200) Nucleotides • 30-200 Daltons 103 -106 Daltons • I.e number of aa’s for spectrin = 230,000 D • 115 H2O

  12. Lipid vesicles are ghost-like 3. Vesicles pass through each other. 2. Pipet pushes vesicle out. 1. Vesicles make contact

  13. Proteins • Primary, secondary, tertiary, quaternary structures • Make filaments: rods, tubes, • Flexural Stiffness

  14. Rod Bending

  15. Polymer Length-stiffness • Persistence length

  16. Acid-base reactions determine charge, that determines mechanical properties . • HA • pKa=pH +log[HA] • [A-] H+ + A-

  17. Cell inside is a gel : a state of matter whereby electro-osmosis produced by charged polymers causes water pressure inside. Cartilage

  18. Structure by light & immunofluorescence PMT Filter

  19. Fibroblasts are stained with Phallacidin green for F actin, Texas red for microtubules, and DAPI for nucleic acid. F actin microtubules

  20. F actin is green with Phalloidin, G actin is red with Texas red. Nucleus has fewer stress fibers, but is thicker than rest of cell, so red is diffuse. F actin G actin

  21. Spectrin Actin Microtubules Intermediate Filaments Heat Cytochalasin Nocodazole Acyrlamide Studying the CSK: “Knock-out” methods

  22. 50% Swelling and Lysis to measure membrane strength • RBCs 3% Muscle Frog

  23. Pipet Aspiration Neutrophils are WBCs involved in immune response. The source of cortical tension is unknown, but may be from actin tangential to surface.

  24. Cells are Wiggly and Soft New ways to describe softness- difference between cooked and uncooked noodles: thermal fluctuations. Neutrophils are WBCs involved in immune response. The source of cortical tension is unknown, but may be from actin tangential to surface.

  25. Fibroblast dividing

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