Exam III: 8

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  1. The Golgi is a __, meaning __.

    Some __ are made in the Golgi as well, such as __.
    • polar structure
    • the enzymes are not hte same from one side to the other
    • polysaccharides
    • algal scales
  2. In plant cells, molecules of the __ are made in the Golgi. __ is not made in the Golgi, but instead made __. 
    What other polysaccharides are made in the Golgi?
    • middle lamella
    • celluluose
    • on the surface of the plasma membrane
    • pectins
    • hemicelluloses
  3. Another function of Golgi?
    What controls the rate of secretion?

    How does a cell sort so that protiens end up int he right place?
    • membrane transformation and origin of lysosomes
    • controlling the rate of synthesis

    proteins that end up in the cytosol have no sorting signal; it is possible for proteins to have more than one signal
  4. Mitochondria has how many places?
    • four
    • inner mitochondrial membrane
    • outer mitochondrial membrane
    • matrix
    • intermembrane space
  5. Targeting to the Matrix of the Mitochondria
    Mitochondria have __ that make about __ of their proteins. __ is in the __.
    • genes
    • 10%
    • 90%
    • cytoplasm
  6. Three pathways into the intermembrane space: 
    • conservative sorting: goes through TOM and TIM complex--> matrix
    • cleavage of sequence--> uncovers another targeting sequence--> directed to intermembrane space
  7. Three pathways into the intermembrane space: 2)
    • nonconservative model
    • starts going through TIM process but is blocked, so remains in space away from channel
    • - there must be a second signal to target it
  8. Three pathways into the intermembrane space: 3)
    • Some proteins go directly through a different channel in the outer membrane, which is very leaky (not TOM, but a differnet channel)
    • - this pathway isn't frequently used)
    • - no evidence of sequence to get to channel
    • - once in the intermembrane space, it folds
  9. Mitochondria are more complex because of what? Same goes for __.
    • the numerous places they can end up in 
    • chloroplasts
  10. Biosynthetic protein traffic:
    - The signals that direct a given protein's movement through the system, and thereby determine its eventual location in the cell, are contained in its __. 

    The journey begins with __ adn terminates when __.

    At each intermediate station, a decision is made as to whether what?

    In principle, a signal could be required either for __ in or for leaving each of the compartments, with the alternative fate being the __.
    • amino acid sequence
    • the synthesis of a protien on a ribosome
    • the final destination is reached
    • to retain the protein or to transport it further
    • retention in
    • "default pathway"
  11. What is the amino acid sequence in mammals that signals retention?
    lys-asp-glu-leu (-COOH end)
  12. What signals retention in the ER?
    a signal peptide
  13. What signals retention in mitochondria?
    ++øø++dd- NH2
  14. Which structures have hte same signal?
    mito and chlor
  15. What controls retention?
    Where is hte info for destination?
    presence or absence of sorting signals; info for destination in the protein
  16. Almost all signals are __.
    signal peptides (one sequence in protein at one end)
  17. Two ways that a protein transport signal can be built into a protein 
    A) The signal is in a __, called a __, that is exposed in the folded protein. __ often occur atthe end of the polypeptide chain, but they can also be located elsewhere. They are normally detected experimentally by their effect on the __ of other protiens when they are attached to them by __.
    • single discrete stretch of amino acid sequence
    • signal peptide
    • signal peptides
    • intracellular sorting 
    • recombinant DNA
  18. Two ways that a protein transport signal can be built into a protein 
    B) A __ can be formed by the __ of amino acids from regions that are physically separated before the protein folds; alternatively, separate patches on the surface of the folded protein that are spaced a fixed distance apart could form the signal. In either case, the __ depends on the 3D conformation of the protein. For this reason it is very difficult to lcate this type of signal precisely.
    • signal patch
    • juxtaposition
    • transport signal
  19. Proteins with the __ are diverted to __ in __. Proteins with signals directing them to __ are concentrated in large __ that lose their coats to become __-- a pathway that occurs only in specialized secretory cells.
    • mannose 6-phosphate marker
    • lysosomes (via endolysosomes)
    • clathrin coated vesicles
    • secretory vesicles
    • clathrin-coated vesicles
    • secretory vesicles
  20. In unpolarized cells, proteins iwth no special features are thought to be delivered to the cell surface by __.
    default via the constitutive secretory pathway
  21. In polarized cells, however, secreted and plasma membrane proteins are __, so that at least one of these two pathways must be signal mediated.
    selectively directed to either the apical or the basolateral plasma membrane domain
  22. If there is missing an enzyme that adds the phosphate group, you will __.
    lack the signal to end up in the lysosome, and end up outside--> no target
  23. In the constitutive secretion pathway, what is not invovled?
    Also called __?
    What signal?
    • clathrin
    • called
    • bulk flow
    • signal sequence
  24. Signal mediated diversion tosecretory vesicles is for __.
    regualted secretio
  25. Transport of newly synthesized lysosomal hydrolases to lysosomes
    - The precursors of lysosomal hydrolase are tagged with __ in the __ and segregated from all other types of prtoeins in the __. The segregation occurs because __ budding from the __ concentrate __, whcih bind the __. These coated vesicles lose their coats and fuse with __.
    • M6P gri=oups
    • cis Golgi
    • trans Golgi network
    • clathrin coated vesicles
    • trans Golgi netwrk
    • mannose 6 phosphate specific receptors
    • lysosomal hydrolases
    • endolysosomes
  26. Transport cont. 
    At the low pH of the __, the __ dissociate from the receptors, which are __. The removal of __ from the mannose on the __ further decreases the chance that the __ will return to the Golgi apparatus with the receptor. Although there are two structurally distinct __ of very different size, tehy have a related amino acid sequnece and appear to have similar functions
    • endolysosome
    • hydrolases
    • recycled to the Golgi apparatus for further rounds of transport
    • phosphate
    • hydrolases
    • hydrolases
    • M6P receptor glycoproteins
  27. What is mannose-6-phosphate?
    the signal that tells where the lysosome will end up
  28. Why does the phosphate group have to leave from the mannose?
    to prevent binding of receptors to receptor enzymes and carried back to the Golgi
  29. ON the lysosomal hydrolase precursor, what then what gets added. 
    The __ signals attachment of proteins to lysosomes.
    • mannose then phosphate
    • signal patch
  30. The regulated and constitutive pathways of secretion diverge in the __. Many soluble proteins are continually secreted from the cell by the __, which operates in all cells. This pathway also supplies the __ with newly synthesized _ and __. Specialized __ also have a regulated __, by which selected proteins in the trans Golgi network are diverted into __, where the proteins are concentrated and stored until an __ stimulates their secretion.
    • trans Golgi network
    • constitutive secretor ypathway
    • plasma membrane
    • lipids nad transmembrane proteins
    • secretory cells
    • secretory pathway
    • secretory vesicles
    • extracellular signal
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Exam III: 8
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