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10 Cards in this Set
- Front
- Back
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Which organelles make up 98% of the membranes in the cell? |
1. ER 2. Golgi 3. Mitochondria 4. Lysosomes 5. Peroxisomes 6. Endosomes |
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How much of the membranes in the cell is the plasma membrane? |
2% |
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What percentage of the membranes does the ER alone take up? |
35-60% |
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where does all translation start? |
on free ribosomes |
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what are the steps of protein targeting to the ER? |
1. signal recognition particle binds to ERss 2. this starts "translation arrest" (stops it) 3. SRP binds to SRP receptor on RER 4. a ribosome binds to the protein translocator 5. SRP and SRP receptor dissolve an recycle 6. ERss enters protein translocator 7. translation begins again 8. rest of protein is transferred into ER 9. translation is complete; protein moves to the side/out of translocon 10. signal pepsidase cleaves ERss |
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how are transmembrane proteins made? |
there are stop-transfer anchor sequences which move that part of the protein out of the translocon before continuing translation. Multiple transmembrane protein have multiple "stop" and "start" sequences |
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How do pancreatic cells work? |
1. They are organized in a polar way 2. the signals are sight/smell of food and food in stomach |
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What were Palade's 3 major conclusions? |
1. ER is site of all secreted protein synthesis 2. Pathway of regulated protein synthesis is: ER>GOLGI>immature secretory granules> zymogen granules>fuse to secrete 3. Secreted proteins are never found free in the cytoplasm |
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What is the pathway for constitutive secretion? |
ER > GOLGI > Vesicles > fuse with PM (secreted and membrane proteins) |
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What is the pathway for regulated secretion? |
ER>Golgi>immature secretory vesicles > zymogen granules (wait for signal) > fuse with PM |
