Mitosis II: Mitosis

a.      1882: __allowed him to observe the behavior of chromosomes during __ and __

Phases of the Cell Cycle
State percentage of time

Interphase 
1.      A cell that is about to divide does what in preparation for cell division
2.      __, during which a cell grows by producing proteins and cytoplasmic organelles like mitochondria ad endoplasmic reticulum, which are __, __, __.         

a.      G₁ (first gap)
                                                                                                                                      i.      __
b.      S phase
                                                                                                                                      i.      __
                                                                                                                                    ii.      __
c.       G₂ phase
                                                                                                                                      i.      __
d.      M phase
                                                                                                                                      i.      __

                                                              i.      Cell may undergo one division in 24 hours
1.      M phase=__
2.      S= __
3.      G₁ =__
a.      Most variable in length in different types of cells
                                                                                                                                      i.      Some don’t divide at all or rarely and spend time in __phase
4.      G₂= __

Phases of Mitosis

                                                              i.      Prophase
1.      __ condense
2.      __disappear
3.      Each duplicated chromosome appears as __ joined at their __and along their __by __(__)
4.     __ begins to form
a.      __ and __; __of shorter microtubules that extend from centrosomes are __
5.      Centrosomes move away from each other, propelled by __
                                                            ii.      Prometaphase
1.      __ fragments
2.      Microtubules now invade __area
3.      Chromosomes more condensed
4.      Each of two chromatids have __, a specialized protein structure at the centromere
a.      Some microtubules attach to these, causing what?
5.      __ interact with those from the opposite pole of the spindle

                                                              i.      Metaphase
1.      __at opposite poles
2.      Chromosomes at __, with __lying at plate
3.      For each chromosome, the __of the__are attached to __ coming from opposite poles

                                                              i.      Anaphase       
1.      __stage
2.      Begins when __
a.      Allows __ of each pair to part suddenlyà __becomes __
3.      Two liberated daughter chromosomes begin moving toward opposite ends of cell as kinetochore microtubules __; microtubules attached to centromere region, they move __first
4.      The cell elongates as the __ lengthen
5.      End of anaphase= __

                                                              i.      Telophase
1.      Two daughter __form in cell
2.      __ arise from fragments of parent cell’s __ and other portions of the __

3.      __reappear
4.      Chromosomes become less condensed
5.      Any remaining spindle microtubules are __
6.      __, the division of one nucleus into two genetically identical nuclei, is now complete

                                                              i.      Cytokinesis
1.      Division of the __is usually well under way by late telophase, so the two daughter cells appear shortly after the end of mitosis
2.      In animal cells, cytokinesis involves the formation of a __, which pinches the cell in two

cytoplasm

a.      The Mitotic Spindle
                                                              i.      Many events depend on it
1.      Begins to form in cytoplasm during __
                                                            ii.      Consists of fibers made of __and __
1.      Material from other __, which disassemble
                                                          iii.    __ elongate by incorporating more subunits of the protein __and shorten by losing subunits

prophase

                                                              i.      Animal cells
1.      Assembly of spindle microtubules starts at __, a subcellular region containing material that functions throughout the cell cycle to organize the cell’s microtubules
a.      In center: __(not important)

                                                              i.      During Interphase:
1.      Single __duplicates, forming two that remain together near nucleusà move apart during __ and __ as microtubules grow out; end of __, they are at opposite ends
a.      An __, a radial array of short microtubules, extends from each centrosome
2.      Spindle includes __,__, and __.

                                                              i.      Each of the two sister chromatids of a duplicated chromosome has a __, a structure of proteins associated with specific sections of chromosomal DNA at each centromere
1.      In opposite directions

                                                              i.      __: some attach to kinetochores (kinetochore microtubules)
1.      When one is captured, the chromosomes begins to move toward the pole from which those microtubules extend, but is checked when other microtubule attaches
a.      Tug of war

                                                              i.      Metaphase: equal pole causes them to be at __

1.      Meanwhile, __not attached elongate, and by metaphase they __and interact with other __ from the opposite pole of the spindle
2.      __have also grown and are in contact with plasma membrane
3.      Spindle complete

                                                              i.      Structure meets function during __
1.      __holding together __ are cleaved by enzyme called separateà __--> move towards opposite ends of cells

a.      Mechanisms for kinetochore movement
                                                              i.      __proteins on kinetochores walk chromosomes along microtubules, which __at their __ends after the motor proteins have passed
                                                            ii.      Reeled in by motor proteins at spindle poles and that the microtubules __after they pass by these __proteins

a.      Nonkinetochore microtubules elongate whole cell during __
                                                              i.      Overlap each other extensively during __

                                                              i.      During __, the region of overlap is reduced as __ attached to the __walk them away from one another, using energy from __
1.      As the microtubules push apart from each other, their __ are pushed apart, elongating the cell
2.      At the same time, the __lengthen somewhat by the addition of __subunits to their overlapping ends, resulting in continuing overlapping

                                                              i.      End of __: duplicate groups of chromosomes have arrived at opposite ends of the elongated parent cell
                                                            ii.      __: nuclei re-form
                                                          iii.      __: begins during __ or __, and the spindle disassembles by __of microtubules

Cytokinesis
a.     
Occurs by __

                                                             
i.     
First: __ (shallow
groove in cell surface near old -_)

b.     
__side: contractile ring
of __ associated with molecules of the protein __

                                                             
i.     
__microfilaments interact with
__molecules, causing ring to __

1.     
Contraction like pulling of
drawstring

                                                           
ii.     
__deepens until
parent cell is pinched in two, producing two completely separated cells, each
with its own nucleus and share of cytosol, organelles, and other subcellular
structures

c.      Plant cells                                                             i.     No __                                                      
ii.     During __, vesicles derivedfrom __move along microtubules to middle of cell, where they coalesce,producing a __
1.     Cell wall materials carried invesicles collect in __as it grows                                                        
iii.     __enlarges until itssurrounding membrane fuses with the __ along the perimeter of cell                                                         iv.     Two daughter cells with own plasmamembrane        1.     New __ arises from contentsof __ forms between cells