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19 Cards in this Set

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Types of Light Microscopy to view Living Cells
1. Bright-Field --> Shows little detailed unless stained
2. Phase-Contrast -->Useful for ordered structures (mitotic spindles)
3. Nomarski -- 3D
4. Dark-field -- Cell is illuminated from side
Flourescence Microscopy Tagging Procedures
1. Flourescent molecule is tagged to an antibody
2. Antibody can be linked to another flourescent molecule
3. Antibody attaches to Antigen
~Can have more than one color
~Use GFP, won't harm cell, to follow in vitro.
~Confocal microscopy allows us to obtain thin optical sections which can be combined for 3D shape.
Fixing Cells for LM
1. Cells are fixed in buffered, isotonic solutions (glutaraldehyde)
2. Fixed cells are wased in buffer, dehydrated in ethonal and embedded in wax.
3. Sectioned by microtome
4. Stained.
Fixing for TEM
~Allows magnification up to 100,000x.
1. Fixed similar to LM. Cells are dead. But postfixed in Osmium tetroxide (lipid structures) and stained in uranyl acetate (nucleic acid) and lead citrate.
~Can use enzymes to digest specific molecules.
Autoradiography (ARG) Procedures
~Useful for identifying molecules and following their movement
1. Cells are exposed to radioactive isotopes for a bit
2. Fixed, dehydrated, embedded, and sectioned.
3. Sections are exposed to silver bromide for several weeks, beta rays from isotope strike and this releases silver grain.
4. Silver grain can be located by LM or TEM
Cell Membrane Fluid Demonstration
Fusing mouse and human cell. Stained lipids and proteins intermingled
Cell Membrane Mosaic Demonstration
Freeze Fracture and sliced through lipid bilayer at hydrophobic tails.
Transmembrane Protein
1. Alpha Helix (18-30 Hydrophobic AA)
2. Beta Barrels
~Must disrupt with Detergent
~Integral
Membrane-Associated Protein
1. Alpha loop inside (doesn't go all the way through) and proteins stick out
2. Integral Protein
Lipid Linked Protein
1. Lipid is inside bilayer which attaches the protein (on the outside)
2. Integral Protein.
Protein Attached Membrane Protein
1. Peripheral, can be removed while leaving membrane intact.
2. Often regulate carriers and receptors
Oligosaccharides Role on Membrane Surface
1. Cell to Cel recognition (immunology and embryonic development)
Tight or Occluding Junctions (TJs)
1. Apical Surface.
2. Ensures molecules take intracellular route
3. More junctions, "tighter" the seal
4. Claudin and Occludin seal plasma membranes
Claudin and Occludin
Transmembrane proteins that seal adjacent plasma membranes in tight junctions
Adheren Junctions
1. Actin Filament
2. Form belt that encircles inner surface of epithelial near apex with 20-30 nm gap
3. Cadherin Molecules extend through membrane and attach to actin filament by catenin
Desmosomes (Focal Adhesions)
1. Bind where there is mechanical stress (blisters)
2. Cadherins span space between plasma membranes
3. Cadherins span plasma membrane and link with intermediate filaments (often Keratin)
Focal Adhesions and Hemidesmosomes
~Both anchor cells to extracellular matrix

Focal Adhesions --> contain integrin proteins that anchor ECM to actin microfilaments

Hemidesmosomes --> anchor ECM to intermediate filaments.
Gap Junctions
1. 2-4nm space between cells
2. Connexons join cells.
3. Increase intracellular calcium levels change connexon conformation and closes channel. Cells dies.
Epidermolysis Bullosa Simplex
Mutations in Keratin, an intermediate filament, that causes blistering.