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25 Cards in this Set
- Front
- Back
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Golgi apparatus |
Consists of an ordered set of membrane enclosed compartments (cisternae) |
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Golgi |
Polarized organelle Movement is bidirectional *Function: - modifies N-linked oligosaccharides (on Asn) - synthesizes O-linked oligosaccharides (on Ser or Thr) - Sorting center (TGN-->lysosome, plasma membrane, secretory vesicles) |
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Golgi Stack |
Contains - Cis face (close to ER) - Trans face (exit, far from ER) |
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Cis face |
Part of golgi stack - close to ER (entry) - Cis golgi network (CGN) |
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Trans face |
Part of golgi stack - far from ER (exit) - Trans golgi network (TGN) |
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ER resident proteins |
possess sorting signals that mediate retention/retrieval to the ER |
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KKXX |
At C-terminal - ER resident membrane protein |
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KDEL |
At C-transport - Soluble - Receptor binds to sequence and packages the protein into COP-I coated vesicles - Receptor cycles between ER and golgi |
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KDEL receptor |
Binds to KDEL sequence and packages the protein into COP-I coated vesicles - High affinity for KDEL in vesicular tubing cluster/golgi to capture KDEL proteins - Low affinity in ER to unload same proteins |
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Lysosomes |
**Membrane enclosed compartments filled with hydrolytic enzymes that are used for controlled intracellular digestion - lumen is maintained at pH 5.0 - membrane separates digestive enzymes out of the cytosol |
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Pathways to deliver materials to lysosomes |
1) Endocytosis 2) Autophagy 3) Phagocytosis |
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Endocytosis |
*Pathway to deliver materials to lysosomes - Cells fully degraded in lysosome after traveling through endosomes |
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Autophagy |
*Pathway to deliver materials to lysosomes - Disposal of obsolete parts of cell itself - Digestion of own mitochondria - Fuses with lysosome to make things inside degraded |
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Phagocytosis |
*Pathway to deliver materials to lysosomes - Ingestion of large particles (engulf) (eg. microorganisms, dead cells) - Bacterium gets engulfed then fuses with lysosomes to degrade vacules |
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M6P receptors |
- Require M6P groups in the TGN and package the hydrolase into clathrin-coated vesicles - Bind to M6P at ph 6.5-6.7 in TGN - Release M6P at ph 6 in the endosome - Empty receptors returned to the TGN |
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Endocytosis |
*Process in which the plasma membrane invaginates and encloses some time of cargo - Different types 1) Phagocytosis (cell eating) 2) Pinocytosis (cell drinking) 3) Receptor mediated endocytosis |
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Phagocytosis |
*Variation of endocytosis - Cell eating: ingestion of large particles via large vesicles (phagosomes) >250nm |
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Pinocytosis |
*Variation of endocytosis - Cell drinking: ingestion of extracellular fluid and solutes via pinocytic vesicles (~100nm) |
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Receptor mediated endocytosis |
*Variation of endocytosis - uptake of specific cargo molecules that bind to receptors in the plasma membrane - form clathrin coats - provides selective concentration mechanisms for taking up molecules from the extracelluar space |
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Cholesterol |
-Transported among tissues by circulation - packaged into lipoproteins for efficient transport |
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Low density lipoprotein (LDL) |
Consists of phospholipids - cholesterol (unesterfied) surface - cholesterol (esters) --cave |
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Exocytosis |
Fusion of vesicles with the plasma membrane and last step of secretory pathways *Transport from the TGN to the cell exterior |
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Two major secretory pathways |
1) Connective secretory pathway 2) Regulated secretory pathway |
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Connective secretory pathway |
*Exocytosis secretory pathway - Transport from TGN to plasma membrane in a steady stream - Default pathway found in all cells |
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Regulated secretory pathway |
*Exocytosis secretory pathway - Cargo is initially stored in secretory vesicles - extracellular signals stimulate their secretion - specialized cells/cargo (eg. hormones, neurotransmitters) |
