1. MULTICELLULAR CELLS CELL DIVISION Test: Thursday Jan. 13 th Cell division, mitosis, meiosis

2. Multicellular Cells  Many celled organisms  Cells are specialized to perform particular functions (can begin as stem cells)  Cells  tissue  organs  organ system What is the same in all of these cells?? DNA!!

3. CELL DIVISION  Causes:  DNA Overload  Repair  Growth  Surface area to volume ratio gets too large

4. Cell Cycle (pg. 245) 1) Interphase 2) Mitosis 3) Cytokenesis

5. The Cell Cycle

6. Interphase  Cell spends about 90% of its time in interphase  GROWTH STAGES:  G1 = normal growth  S = DNA doubles (where mutations can occur)  G2 = organelles double

7. Cell contains large nucleus with visible nucleolus

8. Nuclear division (pgs. 246-248) Mitosis

9. Phases of Mitosis…Prophase Chromosomes become visible

10. Phases of Mitosis…Metaphase Chromosomes line up

11. Phases of Mitosis…Anaphase Chromosomes separate

12. Phases of Mitosis…Telophase Two new identical cells form

13. PLANT vs. cell plate forms ANIMAL cleavage furrow forms Cytokinesis-cytoplasmic division

14. Plant Animal

15. Fig. 12.9

16. Mitosis Video  http://www.sumanasinc.com/webcontent/animations /content/meiosis.html http://www.sumanasinc.com/webcontent/animations /content/meiosis.html

17. Cancer  Uncontrolled cell growth Read stem cell article on page 293

19. N= haploid # of chromosomes found in egg or sperm (gametes) Humans n=23 2N Diploid(2N) =regular chromo# found in body cells (somatic) two identical daughter cells Mitosis only occurs in somatic cells