Understanding Cell Division and Regulation for Healthy Growth

1. Ch. 10 Mitosis The Cell Growth & Division

2. Page 1: • Limits to Cell Growth- 2 main reasons cells divide rather than continuing to grow indefinitely: • More Demands on DNA- • When cell increases in size it does not make extra copies of DNA • If cell grew without limits “information crisis” would occur.

3. Page 1 continue • Exchanging Materials- • Food, oxygen, & water have to enter the cell through the cell membrane • Waste products have to leave • The rate at which this exchange takes place depends on the surface area of the cell (total area of the cell membrane)

4. Page 2 • Ratio of Surface Area to Volume • Volume increases more rapidly than the surface area • Therefore, ratio of surface area to volume decreases This decrease causes serious problems for the cell • If too large becomes to difficult to get enough oxygen and nutrients in and wastes out This is why cells do not grow much bigger even if the organism of which they are a part of does. Quick Lab (p. 242) Analyze & conclude 1-2

5. Page 3 • Define from the chapter: • Cell Division • Mitosis • Chromosome • Chromatid • Draw a picture of chromosome & Chromatid

6. Page 4 • Define from the chapter: 5. Centromere 6. Cell cycle 7. Spindle fibers 8. Centrioles • Draw a picture of Centrioles & Spindle fibers

7. Page 5 • Cell Growth • Describe: • G1- period of activity in which cells do most of their growing. Cells increase in size and synthesize new proteins and organelles • S- Chromosomes are replicated and synthesis of DNA molecules takes place • G2- Many organelles and molecules required for cell divisions are produced • M phase- Mitosis Add Color!

8. Page 6 • Draw, label, & describe the phases of: • Interphase • Prophase Add Color!

9. Page 7 • Draw, label, & describe the phases of: • Metaphase • Anaphase Add Color!

10. Page 8 • Draw, label, & describe the phases of: • Telophase • Cytokinesis-for both plant & animal Add Color!

11. Page 9 Regulating the Cell Cycle: Cell cycle regulators- • early 1980’s biologists found a protein that increased & decreased the time with the cell cycle • They called it cyclin because it seemed to regulate the timing of the cell cycle • Since, they have discovered a whole family of cyclin proteins

12. Page 9 Continued Two types of Regulator Proteins • Internal Regulators- proteins that respond to events inside the cell • Allows cell cycle to proceed only when certain processes have occurred inside the cell • Ex: doesn’t let the cell enter mitosis until all chromosomes have been replicated • External Regulators- Proteins respond to events outside the cell • Direct cells to speed up or slow down cell • Ex: Growth factors- stimulate growth & cycle division of cells. Important in embryonic cells & wound healing

13. Page 10 Uncontrolled Cell Growth Cancer- disorder in which some of the body’s own cells lose the ability to control growth. Cancer cells do not respond to the signals that regulate the growth of most cells, they divide uncontrollably & form masses of cells called tumors that can damage surrounding tissue.

14. Page 10 Continued Two types of tumors: • Benign- does not spread to surrounding tissue (non cancerous) • Malignant- Spreads & destroys healthy tissue (cancerous) Causes: • Biological Agent- viruses • Chemical Agent- carcinogens- tobacco • Physical Agent- radiation

15. Page 10 Continued Treatments: • Surgery • Radiation • Chemotherapy Write a paragraph of your Opinion on Stem Cell Research (p. 253)