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10-2 Cell Division
Photo Credit: © CAMR/A.B. Dowsett/Science Photo Library/Photo Researchers, Inc.
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2. Chromosomes hold genetic information.
Before cell division, each chromosome is copied.

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Chromosomes
“Sister” chromatids: 2 identical chromatids.
Centromere: Each pair of chromatids attached at an area.
Sister chromatids
Photo Credit: © Gunther F. Bahr/AFIP/Stone
Centromere
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The Cell Cycle
During the cell cycle:
a cell grows
prepares for division
divides to form two daughter cells, each of which begins the cycle again
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The Cell Cycle
Cell cycle consists of four phases: G1
S Phase G2
M Phase
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6. Events of the Cell Cycle
During G1, the cell
increases in size
synthesizes new proteins and organelles
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7. Events of the Cell Cycle
During the S phase,
chromosomes are replicated
DNA synthesis takes place
Once a cell enters the S phase, it usually completes the rest of the cell cycle.
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8. Events of the Cell Cycle
The G2 Phase:
organelles and molecules required for cell division are produced
Once G2 is complete, the cell is ready to start the M phase—Mitosis
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9. Events of the Cell Cycle
M Phase
During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases.
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Mitosis
Four phases of Mitosis:
Prophase
Metaphase
Anaphase
Telophase
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Mitosis
Spindle
forming
Prophase is the first and longest phase of mitosis.
Centrioles separate and take up positions on opposite sides of the nucleus.
Centromere
Chromosomes
(paired chromatids)
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Mitosis:Prophase
Spindle
forming
Centrosome: Region containing centromere and organizes spindle.
Spindle: a fanlike microtubule structure that helps separate the chromosomes.
Centromere
Chromosomes
(paired chromatids)
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Mitosis: Prophase
Spindle
forming
Chromatin condenses into chromosomes.
The centrioles separate and a spindle begins to form.
The nuclear envelope breaks down.
Centromere
Chromosomes
(paired chromatids)
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Mitosis
Centriole
Metaphase
The chromosomes line up across the center of the cell.
Microtubules connect the centromere of each chromosome to the poles of the spindle.
Spindle
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Mitosis
Anaphase
The sister chromatids separate into individual chromosomes.
The chromosomes continue to move until they have separated into two groups.
Individual
chromosomes
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Mitosis
Telophase
Chromosomes gather at opposite ends of the cell and lose their distinct shape.
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Mitosis: Telophase
A new nuclear envelope forms around each cluster of chromosomes.
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Cytokinesis
During cytokinesis, the cytoplasm pinches in half.
Each daughter cell has an identical set of duplicate chromosomes
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Cytokinesis in Plants
In plants, a structure known as the cell plate forms midway between the divided nuclei.
Cell plate
Cell wall
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10-2
- or -
(must have QuickTake software installed on the computer you are using for this presentation)
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10-2
The series of events that cells go through as they grow and divide is called
the cell cycle.
mitosis.
interphase.
cytokinesis.
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10-2
The phase of mitosis during which the chromosomes line up across the center of the cell is
prophase.
metaphase.
anaphase.
telophase.
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10-2
Cytokinesis usually occurs
at the same time as telophase.
after telophase.
during interphase.
during anaphase
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10-2
DNA replication takes place during the
S phase of the cell cycle.
G1 phase of the cell cycle.
G2 phase of the cell cycle.
M phase of the cell cycle.
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10-2
During mitosis, “sister” chromatids separate from one another during
telophase.
interphase.
anaphase.
metaphase.
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26. END OF SECTION