Mitosis#2 ii 1
- 2. Why Do Cells Divide??? • DNA Overload - information overload too much cell to make proteins for. • Materials Exchange Problem – Surface Area to Volume Ratio • Injury • Depletion of Cells from natural death.
- 5. Human Chromosomes 23 Homologous Pairs homologous pairs= a matching pair of chromosomes, one from each parent
- 6. • Number of Chromosomes chromosomes depends on characteristics of species • Examples: • Humans 46 (23 pr) Earth worm 36 (18pr) • Fly 8 ( 4 pr)
- 7. Time for cell division depends on type of cell bacteria completes cycle in 22 minutes nerve cell some only once in entire life liver cell may take 1 year
- 8. G1 ~ intense activity & cell growth S phase ~ DNA replication ( will copy every chromosome) G2 ~ prepares for mitosis usually shortest part of interphase organelles needed for mitosis are made now
- 10. Go to Video Clips
- 11. Stages of Mitosis • Prophase • Metaphase • Anaphase • Telophase
- 12. Prophase • Mitosis begins (cell begins to divide) • Centrioles (or poles) appear and begin to move to opposite ends of the cell. • Spindle fibers form between the poles.
- 14. All these cells are in prophase
- 16. Metaphase • Chromosomes line up at the equator of the cell. • Animal cell Plant Cell
- 17. Spindle fibers attach to the chromatids
- 21. Anaphase ~ Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Animal Cell Plant Cell
- 24. Telophase Two new nuclei form. Chromosomes appear as chromatin (threads rather than rods). Mitosis ends. Animal Cell Plant Cell
- 29. Cytokinesis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.
- 31. Division of Prokaryotic Cells (binary fission)
- 34. More Practice
- 39. Cell Cycle
- 40. In lab, we will be looking at the tip of a plant leaf, looking for the different stages of mitosis
- 41. end