Lecture 14

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Lecture 14
2013-03-16 04:24:17
BIS 104

Apoptosis and ECM
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  1. Apoptosis
    Programmed cell death. Nucleus condenses and cell shrivels. Macrophage engulfs.

    A tidy cell death.
  2. Necrosis
    Cell dies and spills contents into surrounding area causing inflammation.
  3. Signal for apoptosis
    Phosphotidyl serine flips to the outside.
  4. Enzyme involved in apoptosis

    • C for cysteine in active site.
    • Asp for target aa which is aspartic acid.
  5. Caspase activation
    Two heavy chains bind releasing prodomains to form active site.

    One activation causes the activation of other caspases.
  6. 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.
  7. Ground substance in plants and animals
    • Plants: Cellulose
    • Animals: Collagen
  8. Cellulose

    Cellulose synthesis/organization
    B1-4 linked glucose, unbranched.

    1) Cellulose synthase complex makes cellulose in the direction of microtubules aligned under membrane.
  9. Cellulose fibrils
    ~ 40 cellulose strings form H-bond to make fibrils w/ tensile strength of steel.
  10. Cellulose framework
    Contains cellulose, pectin, and cross linked glycan.
  11. Collagen
    Protein strands that formed in the ECM
  12. Collagen common aa

    Collagen origination
    Glycine. Protein can twist easier

    ER/Golgi compartiment
  13. 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
  14. 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.
  15. Glycans as signals ideal because
    • 1) Polyhydroxylated and hydrophobic
    • 2) lots of linkage ability