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Chapter 12 The cell cycle

Mastering biology
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Phases of the cell cycle
a. non-dividing cells exit cell cycle.
b. at this point, cells commits to go through the cell cycle.
c. DNA replicates.
d.centrosome replicates.
e. miotic spindle begins to form.
f. cell divides, forming 2 daughter cells.
Mechanisms underlying the events of mitosis
prophase:
* cohesins join sister chromatids of duplicated chromosome.
*tubulins assemble into spindle microtubules.
Prometaphase:
* microtubules attach to kinetochores.
Metaphase:
*kinetochores are motionlessin relation to poles of cell.
Anaphase:
* cohesins break down.
*kinetochores move toward poles of cell.
Telophase:
* spindle microtubules dissemble.
The mitotic spindle
1. During prophase, microtubules of the miotic spindle lenghten.
2. During anaphase, the nonkinetochore microtubules lengthen and move fast past each other,and the kinetochore microtubules shorten.
3. During telophase, the nonkinetochore microtubules disassemble
Roles of the mitotic spindle
1. Will this cell elongate during mitosis? (yes)
2. Will the sister chromatids separate from each other? (yes)
3. Will the chromosomes move to the poles of the cell? (no)
Comparing chromosome separation in bacteria and eukaryotes
bacteria only:
*Chromosome separation begins at the origin of replication on DNA.
Eukaryotes only:
* Before separation, duplicated chromosomes condense.
* Nuclear envelope fragments, permitting chromosome separation.
* 2 copies of the duplicated chromosome are attached at their centromeres before separation.
Both Bacteria and Eukariotes:
* Chromosomes replicate before cell division.
* Replicated chromosomes separate by attaching to some other structural feature of the cell.
Cytokinesis in plant cells: Which of the following statements are true of cytokinesis in plant cells? Select the two that apply
*Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
*The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells.
Cells divide by constriction of a ring of protein
bacteria: TRUE
animals: TRUE
plants: FALSE
The presence of a cell wall prevents the cell from dividing by constriction
bacteria: FALSE
animals: FALSE
plants: TRUE
Tubulin or tubulin-like molecules function in binary fission (in bacteria) or cytokinesis (in animals and plants).
bacteria: TRUE
animals: FALSE
plants: TRUE