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10-2 Cell Division
Photo Credit: © CAMR/A.B. Dowsett/Science Photo Library/Photo Researchers, Inc.
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Cell Division
In eukaryotes, cell division occurs in two major stages.
The first stage, division of the cell nucleus, is called mitosis.
The second stage, division of the cell cytoplasm, is called cytokinesis.
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3. Chromosomes
Chromosomes
Genetic information is passed from one generation to the next on chromosomes.
Before cell division, each chromosome is duplicated, or copied.

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Chromosomes
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Chromosomes
“Sister” chromatids refers to the two identical copies of a single chromosome.
Each pair of chromatids is attached at an area called the centromere.
Sister chromatids
Photo Credit: © Gunther F. Bahr/AFIP/Stone
Centromere
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Chromosomes
When the cell divides, the chromatids separate.
Each new cell gets one chromatid.
The structure of a chromosome:
One long continuous thread of DNA
DNA wraps around proteins called histones
DNA and histones form chromatin (which looks like spaghetti) during interphase
Chromosomes condense tightly for mitosis. Before they are duplicated, they look like half of an X
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The Cell Cycle
Cell Cycle
The cell cycle is the series of events that cells go through as they grow and divide.
Interphase is the period of growth that occurs between cell divisions.
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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
The cell cycle consists of four phases:
G1 (First Gap Phase)
S Phase
G2 (Second Gap Phase)
M Phase (mitosis)
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Mitosis
Mitosis
Biologists divide the events of mitosis into four phases: (PMAT)
Prophase
Metaphase
Anaphase
Telophase
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11. Events of the Cell Cycle
Fill in lines 1, 3, 5, 7, 9-13, 14, 15 in your diagram of the cell cycle
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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12. Events of the Cell Cycle
During G1, the cell (write bullets on line 2 of cell cycle)
increases in size
synthesizes new proteins and organelles
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13. Events of the Cell Cycle
During the S phase, (write bullets on line 4 of cell cycle)
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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14. Events of the Cell Cycle
The G2 Phase (Second Gap Phase) (write bullets on line 6 of cell cycle)
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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15. Events of the Cell Cycle
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
Interphase
Grows
Copies DNA
Duplicates organelles
Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells.
Mitosis
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Mitosis
Spindle
forming
Prophase
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 second phase of mitosis is 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
Anaphase is the third phase of mitosis.
The sister chromatids separate into individual chromosomes and move to opposite sides of the cell
Individual
chromosomes
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Mitosis
Telophase
Telophase is the fourth and final phase of mitosis.
Chromosomes gather at opposite ends of the cell and lose their distinct shape.
A new nuclear envelope forms around each cluster of chromosomes.
Chromosomes begin to uncoil
Spindle fibers fall apart
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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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22. Can you name these phases?

23. Can you name these phases?
1 - Prophase
2 - Metaphase
3 - Anaphase
4 - Telophase
5 - Interphase

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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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