RR Final 1

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  1. What does the cytoskeleton contain?

    Each is a __of __subunits held together by weak, __ bonds

    What does this allow?
    Contains microtubules, microfilaments, and intermediate filaments that together form an elaborate interactive network

    • polymer
    • protein subunits
    • noncovalent

    This allows rapid assembly and disassembly, which is dependent on complex cellular regulation
  2. Microtubules
    long, hollow, unbranched tubes composed of subunits of the protein tubulin
  3. microfilaments
    Microfilaments: solid, thinner structures, often organized into a branching network and composed of the protein actin
  4. intermediate filaments
    Intermediate filaments: tough, ropelike fibers composed of a variety of related proteins
  5. True or False:
    Both prokaryotes and eukaryotes have cytoskeletal or cytoskeletal-like structures
  6. Functions 1 and 2
    • Dynamic scaffold providing structural support that can determine the shape of the cell and resist forces that tend to deform it
    • Internal framework responsible for positioning organelles within cell
  7. Functions 3 and 4 and 5
    • Network of tracts for movement of materials and organelles
    • Force-generating apparatus that moves cells from ne place to another
    • Single-celled organisms crawl or propel themselves through their aqueous environment with help of locomotor organlelles (cilia and flagella)
    • Essential component of the cell’s division machinery
    • Make up mitotic spindle
  8. Experiments
    Concept of __ first derived from tissues viewed with __in 1950s-60s

    Couldn’t show dynamics of it-->__ and __

    __proteins are synthesized with cell fused with __
    • cytoskeleton
    • EM
    • fluorescence microscope and live-cell imaging
    • Fluorescently labeled
    • GFP
  9. In an alternate approach, the protein subunits of cytoskeletal structures are __labeled __by covalent linkage to a small __

    Labeled subunits then microinjected into living cell where incorporated into __, like a microtubule
    Its then followed
    • fluorescently
    • in vitro
    • fluorescent dye
    • polymeric form of protein
  10. If particularly small amounts of fluorescently labeled proteins are injected, the cytoskeletal filaments are no longer what?, but produce __. This is called __.
    • uniformly labeled
    • speckles that serve as fixed markers to follow dynamic changes in length or orientation of the filament
    • fluorescence speckle microscopy
  11. Fluorescence microscopy can be used to reveal __within cell of what?
    _-used because they can ____
    • location
    • a protein present in low concentrations
    • Antibodies
    • distinguish between closely related variants of a protein
  12. Protein __by injecting the labeled __into a living cell, which may also reveal the function of the target protein because attachment of the __generally does what?
    Location can also be determined how?
    • localized
    • antibody x2
    • destroys the ability of the protein to perform in its normal activity
    • by adding the fluorescent antibody to fixed cells or tissue sections
  13. In vitro motility assays make it possible to do what?
    These make it possible to detect the activity of an individual protein molecule acting as a molecular motor in “real time
  14. In some earlier assays, microtubules were attached to a __. Then, micron-sized beads containing attached __were placed onto __by __, which are shone through the objective lens of the microscope, producing a __ near the point of focus   
    Called __
    • glass coverslip
    • motor proteins
    • microtubules
    • laser beams
    • weak attractive point
    • optical tweezers
  15. When ATP is present, the movement of the __along a microtubule can be followed by a __
    __can be used to trap a single bead and determine its forces
    FLAW: __
    • beads
    • video camera
    • Focused laser beams
    • This is indirect because it monitors motility of the beads, not protein molecules
  16. Direct visualization of movement by combining __with __

    __from other areas in the field of view do not obscure the information that emanates from the individual protein molecules whose activities are being monitored
    • fluorescence microscopy
    • specialized imaging techniques
    • Fluorescent light rays
  17. What does it allow
    • comparison of properties of different motor proteins
    • measuring of the properties of individual motors under different experimental conditions
    • asking how a specific mutation of a motor protein affects its motility properties
  18. Fluorescently labeling __and fluorescently labeled __watch interaction of the two types of labeled proteins as they take place within the cell’s cytoplasm under various physiological conditions
    • microtubule polymers
    • kinesin molecules
  19. Although light-microscopic fluorescence techniques can allow researchers to follow the movements of individual protein molecules, they cannot __

    Consequently, these optical techniques do not tell us much about the __
    • resolve the molecules themselves
    • molecular mechanisms by which these proteins actually operate
  20. On the other hand, __ and __ are well-suited for revealing the structure of the molecules but can only provide snapshots of the molecule at a single stage in its operation
    electron microscopic and X-ray crystallographic techniques
  21. New technique allowing high resolution and observation in real time; uses __
    Used to measure the __
    The development of techniques for working with single molecules has coincided with the creation of a new field of mechanical engineering called __
    • AFM
    • mechanical properties of cytoskeletal elements
    • nanotechnology
  22. Goal and uses of nanotechnology
    development of tiny “nanomachines” capable of performing specific activities in a submicroscopic world

    Hopefully, one day, such machines can carry out functions in human body
  23. Dynamic structures are continually undergoing some type of __, whether their old parts are being exchanged with new ones or they are being entirely broken down and rebuilt.
    Thus, even though a __ or __appears __from one moment to the next, its molecular components are in a __
    • rebuilding
    • microtubule or actin filament

    • unchanging
    • state of flux
  24. True or False:
    Changes occur constantly during the cell cycle. Monitoring this requires good technique
  25. Fluorescence recovery after photobleaching (FRAP)
    How to carry out FRAP
    cell is either injected with tubulin coupled to a fluorescent dye or induced to express GFP-tubulin.
  26. Using a microscope with a __that can be focused on a small region of the cell, the fluorescence of the __in that region is __by the __
    Measure the recovery of the signal into the __
    • laser
    • tubulin
    • leached
    • laser beam
    • bleached zone
  27. What can recovery be from?
    dynamics of the microtubules turning over in that bleached zone, growth of new microtubules into the bleached zone, or movement of mcirotubules through the bleached zone
Card Set:
RR Final 1
2013-11-18 18:46:41
Cell Bio

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