RR Final 10 Mitosis: Telophase and Cell Walls

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RR Final 10 Mitosis: Telophase and Cell Walls
2013-11-24 11:22:10
Cell Bio

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  1.                                                               i.      The chromosomes collect in a mass and daughter cells return to interphase condition, which is __/
    mitotic spindle disassembles, the nuclear envelope reforms, and the chromsomes become more and more dispersed until they disappear from view under the microscope
  2. Mitosis requries extensive movements of cellular structures. 
    What are the movements
    • a.       Prophase: mveometn of spindle poles
    • b.      Prometaphase: movement of chromosomes to equator
    • c.       Anaphase A by movement of from spindle and anaphase B by elongation of the spindle
  3. 1.       Different motors involved in mitotic movements, primarily microtubule motors, like __ and __ proteins
    a.       Some motors move toward __and others toward __
    2.       Motor protiens have been localized at the __, along the __ and within both the __and __of the chromosomes
    • cytoplasmic dynein and kinesin-related
    • plus 
    • minus
    • spindle poles
    • spindle fibers
    • kinetochores 
    • arms
  4. 1.       General idea of roles of molecules
    a.       Motor proteins located along the polar microtubules probably contribute by __

    b.      Motor proteins residing on the chromosomes are probably important in the __, __ and __
    • keeping the poles apart
    • movements of the chromosomes during prometaphase, in maintaining the chromosomes at the metaphase plate, and in separating the crhomosoems during anaphase
  5. a.       Motor proteins situated along the overlapping polar microtubules in the region of the spindle equator are probably responsible for __ and__, thus __ during __
    • cross-linkiing antiparallel microtubules
    •  sliding them over one another
    • elongating the spindle during anaphase B
  6. a.       __have a thickened outer coat in addition to their cell membrane, and bacteria, fungi, and plants have distinct cell walls
  7. Functions of cell walls
    - function 1
    Develop turgor pressure that pushes against their surrounding wall, causing a polyhedral shape
  8. Functions of cell walls
    - function 2
    1.       Support for individual cells and serve as a type of “skeleton” for the entire plant
  9. Functions of cell walls
    - function 3
    • 1.       Protect the cell against damage from mechanical abrasion and pathogens, and they mediate cell-cell interactions
    • a.       Source of signals that alter the activities of the cells that it contacts
  10. Structure
    1.       Contain a fibrous element embedded in a nonfibrous, gel-like matrix
  11. a.       __provides the fibrous component of the cell wall and the proteins and __provide the __
    b.      Cellulose molecules are organized into __ that confer rigidity on the cell wall and provide __ to __
    • Cellulose
    • pectin 
    • matrix
    • rod-like microfibrils
    • resistance to tensile (pulling) forces
  12.                                                                                                                                       i.      Each __is about 5 nm in diameter and composed of bundles of __ oriented __to one another and held together by __
    1.       The walls of many plant cells are composed of layers in which the __of one layer are oriented at approximately __ to those of adjacent layers
    • microfibril
    • 36 cellulose molecuels
    • parallel 
    • H bonds
    • microfibrils 
    • ninety degrees
  13. 1.       Cellulose molecules are polymerized where?
    a.       __subunits are added to the end of a __ by a multisubunit enzyme called __
    • at the cell surface
    • Glucose 
    • growing cellulose molecule
    • cellulose synthase
  14.                                                                                                                                       i.      The subunits of the enzyme are organized into a __, which is embedded within the plasma membrane
                                                                                                                                        ii.      In contrast, materials of the matrix are synthesized __ and __
    • 6-membered ring, or rosette
    • within the cytoplasm
    • carried to the cell surface in secretory vesicles
  15. Explain the cellulose matrix.

    The three types of macromolecules that are in the matrix of the cell wall
    highly complex, requiring hundreds of enzymes for its synthesis and degradation

    • hemicelluloses
    • pectin
    • proteins
  16. Hemicelluloses
    structure: branched polysaccharides whose backbone consists of one sugar and side chains of other sugars

    • function: a.       bind to the surfaces of cellulose microfibrils, cross-linking them into a resilient structural network
  17. Pectins
    structure: heterogeneous class of negatively charged polysaccharides containing galacturninic acid

    • function:   Like the glycosaminoglycans of animal cell matrices, pectins hold water and form an extensive hydrated gel that fills in the spaces between the fibrous elements
  18. 1.       When a plant is attacked by pathogens, fragments of pectins released from the wall do what?
    trigger a defensive response by the plant cell
  19. Proteins
    - function
    - Explain one class of proteins, the expansins.
    mediate dynamic activities

    - facilitate cell growth and cause localized relaxation of the cell wall, which allows the cell to elongate at that site in response to the turgor pressure generated within the cell
  20. Cell wall associated protein kinases do what?
    span the plasma membrane and are thought to transmit signals from the cell wall to the cytoplasm
  21. a.       __of the cell wall vary
    Plant cell walls are dynamic structures that can be modified in response to __
    • Percentages 
    • changing environmental conditions
  22. a.       Cell walls arise as a __that forms between the plasma membranes of newly formed daughter cells following __
                                                                  i.      The cell wall matures by the incorporation of additional materials that are __ and __
    1.       In addition to providing __ and __, the cell wall of a young, undifferentiated plant cell must be able to __in conjunction with the __
    • thin cell plate 
    • cell division
    • assembled inside the cell
    • secreted into the extracellular space
    • mechanical support and protection from foreign agents
    • grow 
    • enormous growth of the cell it surrounds
  23. a.       The walls of growing cells are __and they possess an __that is lacking in the __ present around many mature plant cells
                                                                                                                                          i.      The transformation from primary to secondary cell wall occurs as the wall __ and, in most cases, incorporates a phenol-containing polymer called __, which does what?
    • primary 
    • extensibility
    • thicker secondary walls
    • increases in cellulose content
    • lignin
    • Lignin provides structural support and is major component of wood