Term
| What is the structure of the golgi apparatus? |
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Definition
| 3-8 flattened discs. Cis golgi toward ER. Medial and trans golgi face secretory vesicles or lysosomes. |
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Term
| What is the function of the golgi-complex? |
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Definition
| post-translational modifications. (ie glycosylation on lipid and protein molecules as they move through the golgi). Also, dispatch of proteins to where they belong in the cell. (NOTE: usually the oligosaccharide added in the ER is removed in the Golgi and other sugars are added instead) |
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Term
| Which direction do things go through the golgi, and how do they do this? |
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Definition
| They go from cis to trans. This happens both by vesicular transport and by simple maturation of compartments of golgi. |
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Term
| What types of sugars do plasma membrane proteins get added onto them in the golgi? |
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Definition
| sialic acid, fructose, and galactose. These get added/modified during the travel of the protein through the golgi. |
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Term
| wtf is O-linked glycosylation? glycosawho? |
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Definition
| its when glycosylation happens to serine and threonines. sometimes sulfate is involved. |
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Term
| What tags proteins from the golgi to go to the lysosome? |
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Definition
| mannose-6-phosphate is the lysosomal tag. |
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Term
| describe the process of getting the lysosomal proteins from the golgi to the lysosome |
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Definition
| Soooo...you've got that mannose-6-phosphate which binds a receptor for it in the golgi. yeahhh baby. Then adaptins in clathrin coated vesicles bind the M-6-P receptors. Then, the vesicles bud off and go towards the late endosome on a microtubule. The vesicles eventually fuse with late endosomes. The late endosomes have an acidic environment because acid is getting pumped into them. The acidic environment releases the hydrolases from the m-6-p receptor, and they eventually get delivered to their target (the lysosome!). The receptors get recycled back to the golgi. |
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Term
| What happens in the late endosome that makes sure the lysosomal hydrolases don't go back to the golgi? (hint, 2 things) |
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Definition
| 1) the acidic environment releases the hydrolases from their m-6-p receptors. 2) the phosphate from the m-6-p gets removed. |
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Term
| How are lysosomal proteases activated? |
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Definition
| The really low pH of the lysosome makes the 'Pro' region cum off. I think the low pH makes the enzyme basically take the 'Pro' region off. The 'Pro' region is what keeps the enzyme from being active until it is in the lysosome. |
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Term
| Is the whole golgi the same pH? Why is this important? |
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Definition
| No, the trans is the most acidic. This may have to do with KDEL (the thing that binds ER proteins and sends them back to the ER). KDEL might undergo a conformational change that gets it recruited into clathrin vesicles in the lower pH environs of the trans golgi. |
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Term
| What's up with constitutive and regulated secretion from the trans golgi? What does this have to do with signal transduction, I thought that was Krauss' dig? |
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Definition
| yo, so like some shit just goes out unregulated. It just gets secreted by the trans golgi and the vesicles just bring the shit to the plasma membrane. Other stuff gets secreted and stored in a secretory vesicle until it gets mad excited by a signal from a signal transduction pathway. Then it like brings its shit to the plasma membrane and squirts it out. |
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Term
| What do peptide hormone's have before they are fully mature? What does it do? |
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Definition
| They have a 'Pro' region. It assists in protein folding, and sometimes keeps the protein inactive. |
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Term
| How do 'Pro' regions get cut off? |
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Definition
| There are specific proteases that do this. 1-2-3 BRIS!!!!!!!!!!!!!!!!!!!!! |
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Term
| What happens when peptide hormones don't get their 'Pro' cleaved right? Why wouldn't it get cleaved right? |
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Definition
| Mutations within the cleavage sites, or protease mutations, leads to severe endocrine disorders when the peptide hormones don't function (think diabetes, obesity, STERILITY OMG) |
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Term
| Are peptide hormones released constitutively or regulated? |
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Definition
| THEY ARE ONLY RELEASED UPON STIMULATION |
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Term
| What is the mechanism by which peptide hormones stored in storage vesicles get released (eg insulin)? |
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Definition
| So...you get signal transduction which causes activation of potassium channels which lead to opening of calcium channel and influx of calcium. The synaptotagmin-a protein (seriously, i have to fucking memorize this word?) is sensitive to calcium. SO, you get calcium binding at synaptotagmin-a which causes a conformational change which leads to vesicle fusion with the plasma membrane and hormone release. |
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Term
| How do you make a hormone? |
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Definition
| don't pay her. hahahahahahah! |
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Term
| What's different about different parts of the golgi? |
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Definition
| The cis parts have certain enzymes, and the medial has certain enzymes, and the trans has certain enzymes. Also, the pH is lower in the trans (gets progressively lower from cis to trans) |
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Term
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Definition
| Ingest large particles from outside the cell. Ex. bacteria. |
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Term
| What becomes of something ingested by phagocytosis? |
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Definition
| It goes into a phagosome which will eventually fuse with the lysosome. |
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Term
| What are the primary phagocytotic cells? |
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Definition
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Term
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Definition
| Its cellular drinking. When the cell ingests small molecules and fluid. Endocytic vesicles are formed by this. They go to the lysosome to degrade the stuff. |
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Term
| How are cell products broken down? (ie overused organelles) And where does this happen? |
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Definition
| By autophagy. In the lysosome. |
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Term
| What is the mechanism of autophagy? |
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Definition
| A double membrane structure forms around the sequestered material/organelle and then fuses with the lysosomes. |
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Term
| What is receptor mediated endocytosis? |
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Definition
| It is a mechanism for uptake of macromolecules from the extracellular fluid. The macromolecules bind their complementary receptors on the cell surface which triggers endocytosis. |
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Term
| What coats endocytotic vesicles? |
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Definition
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Term
| Where does clathrin bind in terms of the plasma membrane and what does it do? |
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Definition
| It binds the internal surface of the plasma membrane to get a nice vesicular surface. It also has something to do with selection of cargo. |
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Term
| What two transport mechanisms are clathrin involved in? |
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Definition
| Transport from plasma membrane to the endosome, transport from the TGN (golgi) to the late-endosome. |
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Term
| What's a famous receptor that uses clathrin in receptor mediated endocytosis? |
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Definition
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Term
| How do receptors get unattached from their complementary proteins in endocytosis? |
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Definition
| The endosome has an ATP-run H+ pump, which pumps H+ into itself. So, the pH gets lower and the proteins dissociate from the receptors. |
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