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18 Cards in this Set
- Front
- Back
Inclusions
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Components of the cytoplasm with characteristic staining properties; can be membrane-bound or not.
-Secretory vesicles (memb-bound) -Neutral fat (found in adipocytes) -Glycogen (granules 25-30 nm in diameter, often in clusters) -Crystalline inclusions (e.g. in Sertoli and Leydig cells) -Pigments (melanin, hemoglobin) -Stored waste products |
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Glycocalyx
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Extracellular coating of plasma membrane formed from carbohydrate groups attached to:
-Proteins --> glycoproteins -Lipids --> glycolipids |
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Lipid rafts have (higher/lower) concentration of cholesterol and contain (longer/shorter) fatty acids
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higher, longer
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When a freeze fracture is done of a plasma membrane, separating the E (extracellular) and the P (protoplasmic) faces, which contains the majority of the transmembrane proteins?
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P face
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Functions of the plasma membrane
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-pumps
-channels -gap junctions -receptor proteins -linker proteins (anchor intracellular cytoskeleton to ECM) -enzymes (catalyze metabolic rxns) -structural proteins |
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Three variables which can potentially cause the opening/closing of gated channels in plasma membrane
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voltage, ligand, mechanical stimuli
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Three types of endocytosis:
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-Pinocytosis
-Phagocytosis -Receptor-mediated endocytosis |
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Pinocytosis
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-no clatharin, constitutive
-pinched off by dynamin (a GTPase) -abundant in endothelial and smooth muscle cells |
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Phagocytosis
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-no clatharin
-cellular debris, bacteria -Fc receptor on cell surface recognizes Ab -Can also occur without Fc receptor -Actin dependent; requires depolimerization and repolimerization of cytoskeleton |
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Receptor-mediated endocytosis
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-Clatharin-mediated
-Cargo receptors gather in well-defined places on cell surface -Clatharin is recruited to the inner surface where these receptors gather, creating clatharin-coated wells -Dynamin (a GTPase) pinches the vesicle off -Clatharin is recycled to cell surface |
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Exocytosis: two pathways
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-constitutive
-regulated secretory pathway |
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Constitutive exocytosis
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-continuous delivery of proteins to plasma membrane
-Proteins exported after production -occurs in all cells |
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Regulated secretory pathway
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-occurs only in specialized cells (endocrine, exocrine, neurons)
-concentrate proteins and store them in secretory vesicles -regulatory event induces Ca++ influx, stimulating vesicles to fuse with plasma membrane, secreting contents |
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Which membranous compartments have mannose-6-phosphate receptors (M-6-P targets enzymes to serve in the lysosome)?
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Early and late endosomes, lysosomes, and golgi
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Two models to explain endosomal compartments in cells:
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Maturation model (early endosome develops into a late endosome)
Stable compartment model (early and late endosomes are distinct and form stable compartments) |
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Multivesicular bodies
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Transport substances between early and late endosomes
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Function of early endosomes
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sort and recycle proteins internalized by endocytic processes
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Four fates of internalized receptor-ligand complexes
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-receptor recycled, ligand degraded (they separate in the acidic pH of endosome)
-receptor and ligand both recycled -receptor and ligand both degraded -transcytosis (both are transported across the cell) |