Term
| Lysosome structure/content |
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Definition
| contain degradative enzymes (acid hydrolases). Contain proteins for: proton pump to keep pH acidic; transport of digested materials |
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Term
| Safety features of lysosome |
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Definition
| membrane; internal pH optimal for lysosomal enzymes; heavy glycosylation of enzymes/membrane protein inhibit breakdown; membrane contains unusual lipids resistant to degradation |
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Term
| Morphological Identification of lysosomes |
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Definition
| Hard to recognize. But: multivesicular bodies; contain recognizable debris; contain residual bodies (undigested material) |
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Term
| How to accurately identify lysosomes |
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Definition
| histochemistry: acid phosphatase is most common lysosomal enzyme, so organic phosphates and lead salts are added to see where PbPO4 precipitates & then viewed with EM |
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Term
| lysosomal enzyme pathway (synthesis to final destination): |
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Definition
| formed in RER, thru golgi, from trans of golgi to lysosomes via mannose-6-phosphate pathway OR via mannose-6-phosphate independent pathway |
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Term
| mannose-6-phosphate pathway |
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Definition
| transport of lysosomal enzymes from golgi to lysosome: enzymes receive mannose-6-phosphate to N-terminus; M6P binds to receptor in golgi membranes & clathrin-coated vesicles bud off; targeted by receptor complex on lysosome; pH causes M6P to dissociate and can be recycled for further use |
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Term
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Definition
| lysosomal digestion of material from outside the cell via endocytosis (phagocytosis or pinocytosis) |
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Term
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Definition
| lysosomal digestion of parts of cell's own cytoplasm. Occurs more during cell starvation |
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Term
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Definition
| lysosomal digestion of secretory material produced by the cell; happens when product is not likely needed for a long time (e.g. lactation) |
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Term
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Definition
| uptake of substrates from the extracellular space (phagocytosis, pinocytosis, receptor-mediated endocytosis) |
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Term
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Definition
| uptake of matter into large vacuoles called phagosomes. Normally fuse w/lysosomes. |
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Term
| How are bacteria engulfed? |
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Definition
| by phagocytic cells like macrophages. To fuse w/lysosomes, TACO protein must be removed & TB bacillus prevents this. |
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Term
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Definition
| nonspecific uptake of macromolecules & fluid into small vesicles (which lack clathrin coat). Occurs in most cells. |
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Term
| receptor-mediated endocytosis |
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Definition
| uptake of specific materials (e.g. LDLs). Requires binding of macromolecules to specific receptors in membrane. Creates clathrin-coated vesicles. |
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Term
| fates of endocytosed materials |
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Definition
| Recylced. Transcytosis (transported & released at different cell surface). Degradation w/lysosomes |
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Term
| pathway of endocytosed materials to lysosome formation |
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Definition
| early endosome. These turn into MVB (multivesicular bodies), which travel alond microtubles. Turn into late endosomes, which receive lysosomal enzymes from golgi. Turn into lysosomes. |
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Term
| pathway of receptor-mediated endocytosis (LDL as example): |
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Definition
| LDL binds receptor-->Receptors cluster & form clathrin-coated pit-->Pinches off to form coated vesicle-->loses clathrin & fuses w/early endosome-->endosome's low pH dissociates ligand & receptors-->leaves endosome & MVBs carry to late endosomes-->fuse w/lysosome to become new lysosome. |
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Term
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Definition
| cytoplasm/organelles are surrounded by vacuole/sER (autophagosome) and fuses w/lysosome to form autophagolysosome |
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Term
| decreased macrophagy levels leads to |
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Definition
| neurogenerative diseases and cancer |
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Term
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Definition
| non-specific: cytoplasmic proteins enter lysosomes via invagination of lysosomal membrane |
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Term
| Chaperone-mediated direct transport |
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Definition
| specific proteins directed to lysosome by chaperone & interacts w/receptors on lysosome. Activated during starvation. |
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Term
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Definition
| occurs via fusion of membrane of the secretory vesicle w/lysosome |
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Term
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Definition
| eliminates indegestible debris; rarely used, except when cell is stressed; osteoclasts use this |
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Term
| Diseases from defects in gene encoding for a hydrolytic enzyme |
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Definition
| Lysosomal Storage disease: Tay-Sachs, Hurler's, metachromatic leukodystrophy |
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Term
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Definition
| lysosomal storage disease. Deficiency in Beta-hexosaminidase A, which leads to accumulation of GM2 in lysosomes (forms whorls of membranes in lysosomes) |
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Term
| Diseases from defects in processing that lead to incorrect sorting of lysosomal enzymes |
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Definition
| Lysosomal Storage disease: I-cell disease, which fails to create a M6P marker on lysosomal enzymes (& is therefore excreted from cell) |
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Term
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Definition
| proteasomes in the cytoplasm digest damaged/mis-folded proteins marked w/ubiquitin markers |
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Term
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Definition
| single membrane; homogenous; 1-5X bigger than mitochondria |
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Term
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Definition
| degrade lipids & toxins via enzymatic oxidation (yielding H2O2); oxidizes long fatty-acid chains (beta oxidation); catalyzes 1st step in plasmalogen formation (abundand phospholipid in myelin in nervous system); oxidizes ethanol |
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Term
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Definition
| 1) peroxisome fissure or 2) de novo from ER (w/proteins from cytosol) |
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Term
| targeting peroxisomal proteins to peroxisomes |
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Definition
| peroxisomal proteins synthesized on free polysomes w/peroxisomal targeting signal (PTS) bind to cytosol receptors-->transferred to peroxisomes-->binds to docking proteins on peroxisome, which allows enzymes to enter |
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Term
| Class 1 peroxisomal disorder |
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Definition
| patient lacks pathways involving both C & N-terminal targeting sequences, which leads to deficient/empty peroxisomes. Zellweger, NALD |
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Term
| Class 2 peroxisomal disorder |
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Definition
| patient lacks pathway for N-terminal targeting sequence. Rhizomelic chondroplasia. |
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Term
| Class 3 peroxisomal disorder |
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Definition
| enzymatic activity or subcellular location of a single protein is compromised. X-linked adrenoleukodystrophy (ALD). |
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Term
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Definition
| some chemicals can increase # of peroxisomes by up to 10-fold. High-fat diets, aspirin, chemicals, etc. May result in H2O2 accumulation. Could result in cancer thru oxidative damage. |
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