1. Explore how and why cells divide.
Today’s Goal:
Explore how and why cells divide.

3. Cells divide. This makes cells small.
Why do cells divide?
Why must cells be small?

4. Asexual Reproduction Mitosis
Mitosis is the process in which the nucleus divides to form two new nuclei.
How does mitosis differ in plants and animals? 4

5. How do little elephants grow up to be BIG elephants?

7. The process of asexual reproduction begins after a sperm fertilizes an egg.

8. Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.
Cell that reproduce by asexual reproduction reproduce constantly.

9. Asexual – one parent. Offspring identical to parent - mitosis
1. Growth- increase in size of the organism (by dividing cells, not by increasing the size of the cells)
Repair – needed because of worn out or injured cells (your skin cells are replaced every 28 days; your stomach every 7)
3. Reproduction (2 types)
Asexual – one parent. Offspring identical to parent - mitosis
Sexual – combination of genetic material from two parents - meiosis

10. Animated Mitosis Cycle
Interphase
Prophase
Metaphase
Anaphase
Telophase & Cytokinesis

11. Chromosomes are copied (# doubles)
Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase
CELL MEMBRANE
Nucleus
Centromere
Cytoplasm

12. Plant Cell
Animal Cell
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13. Mitosis begins (cell begins to divide)
Centrioles (or poles) appear and begin to move to opposite end of the cell.
Spindle fibers form between the poles.
Centrioles
Sister chromatids
Spindle fibers

14. Plant Cell Animal Cell Spindle fibers Centrioles
Photographs from:

15. Chromatids (or pairs of chromosomes) attach to the spindle fibers.
Centrioles
Spindle fibers

16. Plant Cell
Animal Cell
Photographs from:

17. Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell.
Centrioles
Spindle fibers

18. Plant Cell
Animal Cell
Photographs from:

19. Chromosomes appear as chromatin (threads rather than rods).
Two new nuclei form.
Chromosomes appear as chromatin (threads rather than rods).
Mitosis ends.
Nuclei
Nuclei
Chromatin

20. Plant Cell
Animal Cell
Photographs from:

21. Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

22. Animal Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

23. Plant Mitosis -- Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             

25. - Cell Division 26