Exam 3: RR (8)

  1. a.      important that a cell be able to __
                                                                  i.      this is accomplished as the cell __ 
    1.      __ functions as a major __, directing proteins to various destinations
    • distinguish among the various proteins it manufactures
    • sorts proteins destined for different sites into different membrane-bound carriers
    • trans Golgi network
    • sorting station
  2. a.      lysosomal proteins are synthesized on __ of the ER and carried to the __ along with other types of proteins
                                                                  i.      once in the Golgi cisternae, __ are specifically recognized by enzymes that catalyze the two-step addition of a __
    1.      thus, unlike other __sorted at the __, __ possess __, which act as __
    • membrane-bound ribosomes
    • Golgi complex
    • soluble lysosomal enzymes
    • phosphate group to certain mannose sugars of the N-linked carbohydrate chains


    • TGN
    • lysosomal enzymes
    • phosphorylated mannose residues
    • sorting signals
  3.                                                               i.      lysosomal enzymes carrying a __ are recognized and captured by __, which are integral membrane proteins that span the TGN membranes
    mannose-6-phosphate signal

    mannose-6-phosphate receptors
  4. a.      lysosomal enzymes are transported from the __in __,w hich have a __ and an __
                                                                  i.      __ are escorted from the __by a family of adaptor proteins called __
    • TGN 
    • clathrin-coated vesicles
    • clathrin coated lattice
    • inner coat of receptors
    • lysosomal enzymes
    • TGN 
    • GGAs
  5. a.      GGAs
                                                                  i.      several __, each capable of what?
                                                                ii.      outer ends bind to __, holding the __ onto the surface of the vesicles
    • domains
    • grasping a different protein involved in vesicle formation
    • clathrin
    • clatrhin scaffolding
  6.                                                               i.      on the inner surface, the __ bind to a __ in the __tails of the __
    1.      the __then bind to a soluble enzyme within the __
                                                                ii.      as a result of these interactiosn with __, the __in the __membrane and __ within the __lumen become concentrated into __
    • GGA adaptors
    • sorting signal
    • cytosolic 
    • mannose-6-phosphate receptors (MPRs)
    • MPRS 
    • vesicle lumen
    • GGA adaptors
    • MPRs 
    • TGN 
    • lysosomal enzymes
    • TGN 
    • clathrin-coated vesicles
  7. 1.      production of __ at the TGN begins with the recruitment to the membrane of a small __, in this case __, which sets the stage for the __
    a.      Like Sar1, __extends a membrane-bending __that acts in conjunction with the __ to initiate formation of the __
    • clathrin-coated vesicles
    • GTP-binding protein
    • Arf1
    • binding of the other coat proteins
    • Arf1 
    • alpha helix 
    • clathrin coat
    • budding vesicle
  8.                                                               i.      after the vesicle has budded from the TGN, the __ is lost and the __ proceeds to its destination, which may be an early __,  __, or __
    1.      before reaching one of these organelles, the __dissociate from the __ and return to the TGN for another round of lysosomal enzyme transport
    • clathrin coat
    • uncoated vesicle
    • endosomes, late endosomes, or plant vacuole
    • MPRs 
    • lysosomal enzymes
  9. I.                   Sorting and Transport of Nonlysosomal proteins
    a.      membrane proteins destined for the __ and secretory materials destined for __ are also transported from the TGN
                                                                  i.      __ are produced as the __fragments into __and __of various size and shape
    • plasma membrane
    • export from the cell
    • membranous carriers

    • TGN 
    • vesicles 
    • tubules
  10. a.      fits well with the __
                                                                  i.      proteins that are discharged from the cell by a process of __, like __, are thought to form selective aggregations that eventually become contained in large, densely packed __
    • cisternal maturation model
    • regulated secretion
    • digestive enzymes
    • secretory granules
  11. 1.      these aggregates are trapped as __ bud from the rims of the __and __
    a.      in some cells, long tubules are seen to be pulled out of the TGN by __ that operate along __, which are then split into several vesicles or granules by __
    • immature secretory graneules
    • trans Golgi cisternae and TGN
    • motor proteins
    • microtubular tracks
    • membrane fission
  12.                                                               i.      once they have departed from the TGN, the contents of the secretory granules become more __
    1.      eventually, the mature granules are stored in the __until their contents are released following __of the cell by a __or __
    b.      the targeted delivery of __ to the plasma membrane appears to be based largely on __ in the __ of the membrane proteins
    • concentrated
    • cytoplasm 
    • stimulation 
    • hormone 
    • nerve impulse
    • integral proteins
    • sorting signals
    • cytoplasmic domains
  13. a.      in __cells, membrane proteins destined to reside in the __protion of the plasma membrane contain different sorting signals from those destined for the __ or __ portion
                                                                  i.      these two groups of plasma membrane proteins are clustered into different TGN membrane domains and transported to the cell surface in __
    • polarized 
    • apical 
    • lateral or basal portion

    separate carriers
  14. 1.      plasma membrane proteins of __ cells, like fibroblasts and WBCs, may not require __
    a.      such proteins may simply be carried from the TGN to the cell surface in __of the __
    • nonpolarized
    • specila sorting signals
    • vesicles 
    • constitutive secretory pathway
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Exam 3: RR (8)