Definitions/ Other Structures/ Processes

Card Set Information

Definitions/ Other Structures/ Processes
2013-12-04 20:49:59

Show Answers:

  1. dynamic instability
    - explains what
    Explains the observations that growing and shrinking microtubules can coexist in the same region of a cell and that a given microtubule can switch back and forth unpredictably between growing and shortening phases
  2. dynamic instability relation to plus end
    • Inherent property of the microtubule and more specifically on the plus end
    • Allows the plus ends to rapidly eplore the cytoplasm for appropriate attachment sites and allows rapid response to changes
  3. +TIPS
    • Regulate the rate of the microtubule’s growth or shrinkage or the frequency of interconversion between the two phases
    • Others can mediate attachment of the plus end of the microtubule to a specific cellular structure, such as the kinetochore during cell division
  4. polymerization
    The coming together of dimers to form microtubules; it can push on an attached object
  5. depolymerization
    The breaking down of a microtubule; it can pull on an attached object
  6. intraflagellar transport
    - process
    Process in which particles are moved in both directions between the base of a flagellum or cilium and its tip; the force driving it is generated by motor proteins that track along the peripheral doublets of the axoneme
  7. intraflagellar transport
    - depends on what?
    • Depends on activity of both plus end and minus end-directed movement along microtubules
    • Kinesin 2 moves complex arrays of IFT particles along protofilaments of the peripheral doublets to the assembly site at the tip of the growing axoneme and are transported back toward the basal body along the same flagellar microtubules
  8. Nexin
    Elastic protein that connects adjacent doublets and play an important role in ciliary/flagellar movement by limiting the extent that adjacent doublets can slide over one another
  9. centromeres
    The residence of highly repeated DNA sequences that serve as the binding sites for specific proteins  with a kinetochore at the outer surface of each one
  10. Kinetochores
    Outer surface of the centromere of each chromatid; recruited to the centromere because of the presence of novel nucleosomes containing histones
  11. Kinetochore function
    Functions as the site of attachment of the chromosome to the dynamic microtubules of the mitotic spindle, the residence of several motor proteins involved in chromosome motility ,and a key component in the signaling pathway of an important mitotic checkpoint
  12. Ndc80
    An essential kinetochore component that forms fibrils that appear to reach out and bind the surface of the adjacent microtubule; cells lacking any of the four proteins that make up this complex have severe spindle attachment defects
  13. Ndc80
    • The terminal heads of the Ndc80 complexes are able to travel along the microtubule towards its minus end, pushed along by the curling protofilaments of the disassembling tip
    • as a result, the attached chromosome moves toward the spindle pole as it is towed by the shrinking chromosomal fiber
  14. Separase
    An enzyme that cleaves the proteinaceous link holding the centrioles together even before cytokinesis is over
  15. Gz-S transition
    At this transition is where the initiation of centrosome duplication occurs; triggered by phosphorylation of a centrosomal protein by Cdk2, the same agent responsible for the onset of DNA replication
  16. SCF
    • Add ubiquitin to proteins at different stages of the cell cycle, targeting them for destruction by a proteasome
    • Act primarily during Interphase
  17. APC (anaphase promoting complex)
    • Add ubiquitin to proteins at different stages of the cell cycle, targeting them for destruction by a proteasome
    • Plays a key role in regulating events that occur during mitosis
  18. APC (anaphase promoting complex)
    Structure: contains a dozen core subunits and an adaptor protein that helps determine the APC substrate—Cdc20 and Cdh1
  19. APC^Cdc20
    Activated prior to metaphase and ubiquitinates a key anaphase inhibitor called securin, which secures the attachment between sister chromatids