Mitosis

1. 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 1 continue • 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 2 • Define from the chapter: • Cell Division • Mitosis • Chromosome • Chromatid • Draw a picture of chromosome & Chromatid 5. Centromere 6. Cell cycle 7. Spindle fibers 8. Centrioles • Draw a picture of Centrioles & Spindle fibers

6. Page 3 • 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!

7. Interphase • G1 phase (gap) growth & metabolic activity • S phase (DNA replication) • G2 phase (gap) cells prepares for division • Mitosis • Cytokinesis (cytoplasmic division)

8. Page 4 • Draw, label, & describe the phases of: • Interphase • Prophase Add Color!

9. Page 5 • Draw, label, & describe the phases of: • Metaphase • Anaphase Add Color!

10. Page 6 • Draw, label, & describe the phases of: • Telophase • Cytokinesis-for both plant & animal Add Color!

11. A Cell’s Appearance During Interphase Plasma membrane Nucleoplasm Cytoplasm Nuclear envelope

12. Prophase • Replicated chromosomes, which are being held together by a centromere, condense. • Centrioles move to opposite poles of the cell. • Nuclear envelope and nucleolus disperse. • Microtubules are assembled from tubulin proteins in the cytoplasm, and these structures associate with the centrioles and the chromosomes. • A spindle-shaped array of microtubules (spindle fibers) forms between the centrioles as they move apart.

13. Metaphase • The doubled chromosomes become attached to the spindle fibers by their centromeres. • The chromosomes begin to line up on the midline

14. Anaphase • The centromers split apart and chromatid pairs from each chromosome separate from each other • The chromatids are pulled apart by the shortening of the microtubules in the spindle fibers.

15. Telophase • The chromatids reach the opposite poles of the cell. • The spindle breaks down, the nucleolus reappears, & a new nuclear envelope forms around each set of chromosomes. • A new double membrane begins to form between the 2 new nuclei.

16. Cytokinesis • Animal Cells- the plasma membrane pinches in along the equator and 2 new cells are separated. • Plant Cells- Have a rigid cell wall, so the plasma membrane does not pinch in. • The cell plate is laid down across the cell equator. • A cell membrane forms around each cell, & new cell calls form on each side of the cell plate until separation is complete.

17. Mitosis Animation • Mitosis Animation

18. Now, name and then order these phases of mitosis. A B C D E F G H I

19. Page 7 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

20. Page 7 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

21. Page 8 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.

22. Page 8 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 • Genetics

23. Page 8 Continued Treatments: • Surgery • Radiation • Chemotherapy The End

24. Onion Root Tip • Under Low Power… • Look for this 1st then SWITCH TO HIGH POWER!!!!!

25. Onion Root Tip • Identify the stages

26. Onion Root Tip

27. Page 9 • DNA Scientists Chart

28. Pg. 10 • DNA NOTES

29. Pg. 11 • DNA REPLICATION