MITOSIS Why do cells reproduce How do cells

MITOSIS Why do cells reproduce? How do cells reproduce? What controls cell division? What is the relationship between mitosis and tumors?

Figure 12. 3 Chromosome duplication and distribution during mitosis

Why do cells need to divide? Some organisms divide in order to reproduce (asexual reproduction) • Organisms like humans rely upon cell division in order to grow, and to replace old or damaged cells •

Mitosis Vocabulary 1. Mitosis - the first stage of cell division when the nucleus divides 2. Cytokinesis – the second stage of cell division, when the cytoplasm divide 3. Parent cell - the cell that is dividing 4. Daughter cells- the two new cells that form from mitosis

Mitosis Vocabulary 5. Centriole - a small structure located near the nucleus; it creates the spindle (in animal cells only) 6. Spindle - a fibrous, oval-shaped structure formed by the centrioles during mitosis 7. Nucleus - where DNA is found in a eukaryotic cell

Mitosis Vocabulary 8. Chromosomes (DNA threads) – genetic material within the cell that controls the cell’s activities. 9. Chromatids – sister strands of a replicated chromosome attached at the centromere. 10. Centromere - the area (near the middle) where sister chromatids are attached to each other.

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Cell Cycle

Prophase • • • Longest phase Replicated chromosomes become shorter and thicker (condensed) Nuclear membrane disappears Centrioles begin to separate The spindle (tiny threads) forms between the centrioles

Prophase

Metaphase (line up in Middle) • • • Shortest phase Centrioles finish separating and the spindle is completely formed The replicated chromosomes line up SINGLE FILE in the middle of the cell

Metaphase

Anaphase (sister chromatids pull Apart) • • • Sister chromatids separate One set moves to each end or pole Ends when chromosomes stop moving

Anaphase

Telophase (makes Two new cells) • • • The nuclear membrane reforms around each nucleus The spindle (tiny threads) disappears Each centriole is located outside of each new nucleus Chromosomes become longer and thinner and then disappear One cell separates into two identical cells (cytokinesis)

Telophase

Cytokinesis Occurs at the same time as telophase • The cell membrane pinches inward in most animal cells •

Mitosis in Plant Cells § § Plants have no centriole, but the spindle still develops Plant cell cytoplasm separates into two parts by the formation of a cell plate. This becomes the cell wall of the new plant cells.

See what you know! The following are different stages of mitosis. See if you can identify what stage the cell is in.

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