1. Making more cells, so life can continue
CELL DIVISION
Making more cells,
so life can continue

2. Chromosomes Cell division involves copying chromosomes (DNA)
and then dividing
them among cells

3. Chromosomes
2 Types:
Autosomes: chromosomes not directly involved in determining gender
(22 pairs- in humans)
Sex chromosomes: chromosomes directly involved in determining gender
(1 pair- XX [girl] or XY [boy])
*23 pairs of chromosomes in humans- 46 total chromosomes

4. 2 Types of Cell Division
Mitosis- occurs in regular body cells of an organism
(ex. Skin cells)
Meiosis- occurs in the gametes (sex cells) of an organism
(ex. Sperm and Eggs)

5. Cell Cycle
Cell cycle: repeating sequence of cellular growth and division during an organism’s life
make more cells

6. Steps of Mitosis 0) Interphase:
G1: Chromosomes are not visible; cell is growing
S: Chromosomes replicate (DNA synthesis)
Each chromosome is now made of TWO sister chromatids joined at a centromere
Same # of chromosomes, just double genetic info.
G2: Centrioles and other organelles replicate

7. Interphase Video

8. Steps of Mitosis 1) Prophase (START of Mitosis)
Chromosomes condense; now visible
Nuclear Membrane disappears
Centrioles migrate to poles (opposite ends of cell); spindle fibers form between them

9. Prophase Video

10. Steps of Mitosis 2) Metaphase
Chromosomes attach to spindle fibers at centromere
Spindle fibers pull the chromosomes to the middle of the cell

11. Metaphase Video

12. Steps of Mitosis 3) Anaphase Spindle fibers shorten
Sister chromatids are pulled apart; opposite ends of cell

13. Anaphase Video

14. Steps of Mitosis 4) Telophase Nuclear Membrane reforms
Spindle fibers disappear
Chromosomes uncoil (invisible)

15. Telophase Video

16. Steps of Mitosis 5) Cytokinesis
Cell splits in TWO as cell membrane encloses each new cell
Two genetically identical diploid* cells
*Diploid= 2 sets of chromosomes

17. Mitosis Video QUIZ

18. Cancer and Cell Division
CancerQuest Video
Read pg. 126 in text
How does cancer relate to cell division?
In what ways could scientists keep cancer cells from dividing/spreading?
What preventive measures can reduce the chances of getting cancer?
11 minute video

19. References
Mitosis and Meiosis. Ancient Lights Discovery Education. 17 November 2009 <
Johnson & Raven. (2007) Biology. (CA ed.) Holt, Rinehardt, Winston. Austin, TX.
Mitosis pictures: