Lecture 2 Monday, January 26, 2004

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Lecture 2Monday, January 26, 2004

• Survey
• Introduction continued CSK, tensegrity.
• Basic cellular components

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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.)
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Nucleus connected to the CSK, modeled with straws.
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Tensegrity
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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
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Percolation an alternate theory
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Malines, Belgium
Fibroblast
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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.
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Cells incorporate into Nano-fabricated
devices Attaching to needles Stretching on
a cantilever Growing on electrodes
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The generic cell Basic structure And components
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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 aas for spectrin 230,000 D
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  115

H2O
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Lipid vesicles are ghost-like
3. Vesicles pass through each other. 2.
Pipet pushes vesicle out. 1. Vesicles make
contact
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Proteins

• Primary, secondary, tertiary, quaternary
  structures
• Make filaments rods, tubes,
• Flexural Stiffness

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Rod Bending
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Polymer Length-stiffness

• Persistence length

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• Acid-base reactions determine charge, that
  determines mechanical properties .
• HA
• pKapH logHA
• A-

H A-
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Cell inside is a gel a state of matter whereby
electro-osmosis produced by charged polymers
causes water pressure inside.
Cartilage
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Structure by light immunofluorescence
PMT
Filter
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Fibroblasts are stained with Phallacidin green
for F actin, Texas red for microtubules, and DAPI
for nucleic acid.
F actin
microtubules
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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
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Studying the CSK Knock-out methods

• Spectrin
• Actin
• Microtubules
• Intermediate Filaments

• Heat
• Cytochalasin
• Nocodazole
• Acyrlamide

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Swelling and Lysis to measure membrane strength

• RBCs

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