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Apoptosis
Programmed cell death. Nucleus condenses and cell shrivels. Macrophage engulfs.
A tidy cell death.
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Necrosis
Cell dies and spills contents into surrounding area causing inflammation.
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Signal for apoptosis
Phosphotidyl serine flips to the outside.
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Enzyme involved in apoptosis
Caspases.
- C for cysteine in active site.
- Asp for target aa which is aspartic acid.
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Caspase activation
Two heavy chains bind releasing prodomains to form active site.
One activation causes the activation of other caspases.
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Extracellular matrix
1) Composed of proteins and polysaccharides.
2) Has ground substance for tensile strength + resistance.
3) Molecules in ground substance promotes adhesion, communication, and migration.
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Ground substance in plants and animals
- Plants: Cellulose
- Animals: Collagen
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Cellulose
Cellulose synthesis/organization
B1-4 linked glucose, unbranched.
1) Cellulose synthase complex makes cellulose in the direction of microtubules aligned under membrane.
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Cellulose fibrils
~ 40 cellulose strings form H-bond to make fibrils w/ tensile strength of steel.
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Cellulose framework
Contains cellulose, pectin, and cross linked glycan.
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Collagen
Protein strands that formed in the ECM
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Collagen common aa
Collagen origination
Glycine. Protein can twist easier
ER/Golgi compartiment
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Collagen production
- 1) synthesis of pro-alpha chain
- 2) hydroxylation of specific proline and lysine
- 3) Glycosylation of hydroxylated residue
- 4) self assembly of 3 pro-alpha chain
- 5) move to ECM + cleavage of extra aa
- 6) Self assembly into fibrils
- 7) aggregation of fibrils
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Glycosaminoglycans
Unbranched polysaccharide chain composed of repeating disaccharide units.
- Saccharide #1: Amino sugar, usually sulfated.
- Sacchardie #2: Usually uronic acid, COOH on C6.
Lots of negative charges so it repels water and each other and extends. Forms gels and expands in water.
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Glycans as signals ideal because
- 1) Polyhydroxylated and hydrophobic
- 2) lots of linkage ability
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