Transcript Cell Cycle - Saint Paul Public Schools

Cell Cycle
Why do cells divide?
• Growth: from
childhood to adult
• Repair: skin cells, cell
lining of stomach all
need to be replaced
• Reproduction: egg
and sperm are formed
Three Steps in Cell Cycle
• Interphase
– Cell grows and prepares for division
– 90% of time
– Chromosomes copy themselves
• Mitosis- 4 steps of nuclear division
• Cytokinesis- division into two new cells
4 steps:
–
–
–
–
Mitosis
Prophase
Metaphase
Anaphase
Telophase
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Prophase
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• chromatin is
developing into
chromatids
• Centrioles are
moving toward poles
and spindle fibers are
forming
Metaphase
• nuclear membrane
disappears.
• chromatids line up
on the metaphase
plate.
• spindle fibers are
connected to the
sister chromatids at
the centromere.
Anaphase
• the sister chromatids
separate by the pulling
action of the centrioles
on the spindle fibers.
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Telophase
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• The chromatids pulled
to poles.
• The nuclear membrane
is reforming
Cytokinesis
• Cytokinesis and telophase take place at approximately the
same time.
•Where mitosis is the division of the nucleus, cytokinesis is
the division of the cytoplasm.
•Once the division of the cytoplasm is complete, two new
cells have formed.
Answer the following questions
1. Is this an animal or a
plant?
2. What phase is this
slide in?
3. What helped you
determine which
phase this slide was
in?
Answer the following questions
4. Is this an animal or a
plant?
5. What phase is this
slide in?
6. What helped you
determine which
phase this slide was
in?
Answer the following questions
7. Is this an animal or a
plant?
8. What phase is this
slide in?
9. What helped you
determine which
phase this slide was
in?
Answer the following questions
10. Is this an animal or
a plant?
11. What phase is this
slide in?
12. What helped you
determine which
phase this slide was
in?
Answer the following questions
13. What phase is the
cell the arrow is on
in?
14. What phase is the
cell to the left of that
cell in?