Key Concepts of Section 4.4

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Key Concepts of Section 4.4

Isolation of Cell Organelles

  • Microscopy has revealed a common set of organelles that are present in eukaryotic cells.

  • Disruption of cells by vigorous homogenization, sonication, or other techniques releases their organelles. Swelling of cells in a hypotonic solution weakens the plasma membrane, making it easier to rupture.

  • Sequential differential centrifugation of a cell homogenate yields fractions of partly purified organelles that differ in mass and density.

  • Equilibrium density-gradient centrifugation, which separates cellular components according to their densities, can further purify cell fractions obtained by differential centrifugation.

  • Immunological techniques using antibodies against organelle-specific membrane proteins are particularly useful in purifying organelles and vesicles of similar sizes and densities.

  • Proteomic analysis can identify all the protein components in a preparation of a purified organelle.