SolutionProblemSetF - BILD 1 Halpain 2009 Problem set F KEY...

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BILD 1 Halpain 2009 Problem set F KEY 1.a. Name three reasons why cells must regulate their division. 1. During growth and development different cell types must divide at different rates to create a functional organism. 2. Following an injury or illness, it may be necessary for cells that are normally in the non-dividing state to divide once more to repair damaged tissue. 3. Cells that exhibit uncontrolled division form cancer cells. b. What occurs at each of the following checkpoints in the cell cycle? What happens if a cell does not meet the criteria required to pass each checkpoint? G1 -This is the point where cells make the critical decision whether or not to divide. At this checkpoint, the cell checks to ensure that internal and external environments are favorable for division. If this is not the case, the cell enters its resting state, G0. G2 -Here, the cell checks to see whether all DNA has been properly replicated and prepares to initiate the events of mitosis. If the cell fails to meet the criteria for mitosis to begin, the cell cycle is arrested. M -At the metaphase checkpoint, the cell makes sure that all replicated chromosomes are properly aligned at the cell’s midline. If so, the cell proceeds with mitosis and the daughter cells enter the G1 phase of the cell cycle. 2.a. There are three types of microtubules involved in cell division. Name each type and describe their roles in mitosis. Kinetochore tubules directly link the kinetochore of the replicated chromosomes to the centrosomes. They then begin to shorten, pulling the chromosomes towards opposite poles of the dividing cell. Non-Kinetochore microtubules do not contact the kinetochores but rather contact each other from opposite poles of the cell. The interaction between them creates a pushing force that helps the cell to elongate prior to cytokinesis. Aster Microtubules anchor the centrosomes to the cell’s plasma membrane.
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This note was uploaded on 12/17/2009 for the course BIOL 1 taught by Professor Patrick during the Fall '09 term at CSU Northridge.

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SolutionProblemSetF - BILD 1 Halpain 2009 Problem set F KEY...

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