CellBio-8

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Author:
canucks
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110256
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CellBio-8
Updated:
2011-10-21 15:15:34
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Cell Biology
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Chapter 8
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  1. What do membranes do?
    Membranes divide cytoplasm of eukaryotic cells into disticnt comartments.
  2. The endomembrane system includes organelles such as the?
    • Endoplasmic Reticulum
    • Golgi Complex
    • Endosomes
    • Lysosomes
    • Vacuoles
  3. Materials are shuttled between organelles in ___ transport vesicles.
    membrane-bound
  4. What is an acceptor compartment?
    When the vesicles reach their destination, vesicles fuse with the membrane of the acceptor protein.
  5. What occurs in the Biosynthetic Pathway?
    Synthesis, modification and transport of proteins.
  6. What occurs in the Secretory Pathway?
    When proteins are discharged (secreted) from the cell. There are 2 types: constitutive, and regulated.
  7. What happens during regulated secretion?
    Materials to be secreted are stored in membrane-bound secretory granules.

    Example: secretion of digestive enzymes by pancreatic cells.
  8. One way to approach the study of cytomembranes is by Autoradiography, explain it.
    Autoradiography uses readiolabeled materials that are exposed to photographic films to visualize biochemical processes.

    Example: Used to determine where secretory proteins are synthesized.
  9. Green Flourescent Protein is another appoach to the study of cytomembranes. Explain it.
    Green Flourescent Proteins are proteins that are isolated from jellyfish which emits a green flourescent light. A GFP-DNA chimera allows observation of protein synthesis in cell. Protein traffic.
  10. Give some insights from f Cell-Free Systems
    • -do not contain whole cells
    • -have provided information about the roles of proteins involved in membrane trafficking

    • **Other type of info..
    • -proteins that bind to the membrane to initiate vesicle formation
    • -proteins responsible for cargo selection
  11. Why study mutants when learning about cytomembranes?
    They provide insights about function of normal gene products. Isolation of proteins from yeast has led to the indentification of homologous proteins in mammals.
  12. Describe RNA Interference.
    Cells produce small RNAs that bind to specific mRNAs and inhibit translation. Scientists can identify genes involvded in a particular process by determining which RNAs interfere with that process.
  13. What are the 2 components of the endoplasmic reticulum?
    Rough Endoplasmic Reticulum + Smooth Endoplasmic Reticulum
  14. Has a network of flattened sacs (cisternae)
    RER
  15. Is continuous with the outer membrane of the nuclear envelope.
    RER
  16. Has ribosomes on its cytosolic surface.
    RER
  17. This membrane type is extensively developed in some cells.
    SER
  18. Funstion: synthesis of steroid hormones in endocrine cells.
    SER
  19. Function: detoxification in the liver of various organic compounds.
    SER
  20. Function: sequestration of calcium ion into cytoplasm of muscle cells.
    SER
  21. What is the starting point of the biosynthetic pathway?
    RER
  22. Functions: polarity of RER in some cells reflects the flow from the site of protein synthesis to the site of discharge of the protein.
    RER
  23. Name three types of polypeptides that are synthesized on RER ribosomes of RER.

    **S.I.S.**
    • 1. Secreted proteins
    • 2. Integral membrane proteins
    • 3. Soluble proteins of organelles
  24. Polypeptides synthesized on "free" riobosomes include ___ of those encoded by the human genome. (its a percentage)
    1/3
  25. (RER)

    What binds to free ribosomes on cytosol?
    Messenger RNA
  26. Slide 19
    look at it
  27. What the fuck can you say about membrane biosynthesis in the ER
    • - membranes arise from pre-existing membranes
    • - lipids are inserted into existing membranes
    • - as the membrane moves one compartment to the next, its proteins and lipids are modified
    • - membrane asymmetery is established initially and maintained during trafficking
  28. 1. Where are the majority of membrane lipids synthesized?
    2. What are some exceptions?
    1. Most membrane lipids are synthesized in the ER

    2. Sphingomyelin, glycolipids, and some unique lipids of mitochondria and chloroplasts
  29. Tell me 3 things about Glycosylation in RER
    1. Catalyzed by glyocosyltransferases

    2. Core segment of each carbohydrate chain is put together on a lipid carrier (dolichol phosphate) and then transferred to a polypeptide

    3. Core carbohydrate is modified by oligosaccharyltransferase as the polypeptide is transferred into the ER lumen
  30. During glycosylation in the RER, a ___ goes through a system of quality control to determine its fitness for a specific compartment.
    glycoprotein
  31. Misfolded proteins are tagged by a ___ and recognized by chaperones for refolding
    terminal glucose
  32. Misfolded proteins are transported into the cytosol where they are destroyed in ___
    proteasomes
  33. What does ERAD do?
    Ensures the misfolded proteins do not reach the cell surface

    Look at slide 29
  34. Tell me 3 things about the golgi complex.
    • 1. Stack of flattened cisternae
    • 2. Divided into several functionally distinct compartments
    • 3. The cis face of the Golgi face the ER, the trans face is on the opposite side of the stack
  35. What does the cis golgi network (CGN) do?
    Sorts proteins for the ER or the next gogi station
  36. What does the trans golgi network do?
    Sorts proteins either to the mebrane orvarous intracellular destinations.
  37. Is the golgi complex uniform in composition?
    No, there are differences in composition from the sis to the trans face
  38. Materials are carried between compartmentss using ___
    coated vesicles
  39. What are the 2 functions of protein coats?
    1. Cause membrane to curve and form a vesicle

    2. Select components to be carried by vesicle
  40. What do COPII-coated vesicles do?
    Move materials from the ER "forward" to the ERGIC and golgi complex
  41. What do COPI-coated vesicles do?
    Move materials fromERGIC and golgi "backward" to ER, or from the trans golgi to the cis golgi cisternae
  42. What do Clathrin-coated vesicles do?
    Move materials from the TGN to endosomes, lysosomes, and plant vacuoles.
  43. Adenosylation ribose factor 1 (ARF1), a G protein, is required for what?
    vesicle transfer between cisternae
  44. Proteins are maintained in a organelle by two mechanisms, what are they?
    1. Retention or resident molecules that are excluded from transport vesicles

    2. Retrieval of "escaped" molecules back to the compartment where they reside
  45. Lysosomal enzymes are transported from the TGN in what kind of protein vesicles?
    Clathrun-coated
  46. The discharge of a secretory vesicle or granule after fusion with plasma membrane is called ___
    exocytosis
  47. What is triggered by an increase in Ca2+
    Exocytosis
  48. ___ contain acid hydrolases which can digest type of biological molecule
    Lysosomes
  49. The low pH optimum of these enzymes is maintained by a proton pump (H+ - ATPase)
    Lysosomes
  50. ___ play a key role in organelle
    Lysosomes
  51. This results from a deficiency in an enzyme responsible for degrading gangliosides, a major component of cell membranes.
    Tay-Sachs
  52. Plant cell vacuoles ___ membrane bound, fluid filled compartments.
    are
  53. Do plant vacuoles contain acid hydrolases?
    yes
  54. This is the uptake of cell surface receptors and bound extracellular ligands.
    Endocytosis
  55. This is the uptake of particulate matter
    Phagocytosis
  56. -nonspecific uptake of extracellular fluids is endocytosis, but what kind
    pinocytosis
  57. What is receptor mediated endocytosis
    The uptake of specific extracellular ligands following their binding to receptors
  58. Following internalization, vesicle bound materials are transported in vesicles and tubules known as ___
    endosomes
  59. These transport cholesterol from tissues to the liver for excretion.
    High-Density Lipoproteins (HDLs)
  60. The uptake of large particles
    phagocytosis
  61. Engulfment of particles by phagocytosis is driven by ___
    actin containing microfilaments
  62. Most chloroplast proteins are imported from ___
    cytosol

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