1. Cell Division Chapter 10

2. Limits to Cell Growth DNA Overload Exchanging Material
The larger a cell becomes, the more demands the cell places on its DNA
Exchanging Material
The cell has trouble moving enough nutrients and wastes across the cell membrane if the cell is too big.
Surface Area:Volume ratio can’t be too small

4. Cell Cycle

5. Cell Cycle Interphase (inter- means “between”) M phase G0 phase
G1 phase – Cell growth
S phase – DNA replication
G2 phase – preparation for cell division
Cells are in interphase most of the time.
M phase
Mitosis: prophase, metaphase, anaphase, telophase, cytokinesis
G0 phase
Cells that cannot divide like nerve cells, red blood cells, and cardiac cells

6. Prophase Chromosomes condense into sister chromatids
Plant cells in prophase
Prophase
Chromosomes condense into sister chromatids
Chromatids are joined by a centromere
Centrioles appear and form mitotic spindle
Nucleolus disappears and nuclear envelope dissolves
Longest phase of mitosis (50-60%)
Pair of centrioles

7. Anatomy of a Chromosome

9. Metaphase Centrioles on opposite ends of the cell
Animal cell
Plant cell
Centrioles on opposite ends of the cell
Microtubules of mitotic spindle attach to the centromeres
Chromosomes line up across the middle (equator) of the cell

10. Anaphase Sister chromatids separate
Early anaphase (plant)
Late anaphase (plant)
Sister chromatids separate
Chromosomes migrate to opposite ends of the cell
Anaphase (animal)

11. Telophase Chromosomes begin to disperse Nuclear envelopes reform
Plant cell
Animal cell
Chromosomes begin to disperse
Nuclear envelopes reform
Mitotic spindle breaks apart

12. Cytokinesis Difficult to distinguish from telophase
Animal cell
Plant cell
Difficult to distinguish from telophase
In animal cells the cell membrane pinches in forming two daughter cells
In plant cells a cell plate forms between the daughter nuclei and a new cell wall forms at the cell plate

13. Mitosis animations Cells alive http://www.cellsalive.com/mitosis.htm
Vcell
PBS

16. Controls on Cell Division
When cells are touching each other, they tend to stop growing and dividing.
Cyclins are proteins that regulate when a cell divides.
Internal regulators respond to environment within the cell.
External regulators respond to environment outside of the cell.

17. Cancer Uncontrolled cell growth Cancer cells smother normal cells
Caused by smoking, exposure to radiation or certain chemicals, some viruses
Cancer cells smother normal cells
Treatment options
Surgery to remove tumor
Radiation therapy to halt cell division
Chemotherapy to halt cell division