1. Starter 1. What is the purpose of cell division? 2. What are the 3 major steps and what happens in each of the cell cycle? 3. Why must DNA replication happen before mitosis and cytokinesis? 4. What are the phases of mitosis? 5. With a pencil, label your drawings with the stages of the cell cycle, the phases of mitosis and cytokinesis.

2. Where we have been.  Cells  Organelles Nucleus DNA Replication Chromosomes

3. Curious?  Asexual reproducers  Archea  Bacteria  Protists  Starfish  Sexual reproducers (pregnancy length)  Birds  Humans (9 months)  Insects  Rabbit (33 Days)  Alpine Salamander (38 months)  Elephant (22 months)

4. Starter  Using 9.1 complete the reproduction venn diagram on the front table

5. Asexual Vs. Sexual Reproduction  Reproduction – 2 types  Asexual One Parent Offspring genetically identical to the ONE parent Quick Many offspring  Sexual Two Parents Offspring share genetic information from BOTH parents Creates variation (offspring genetically different) Slower Few offspring

6. Chromosomes  Chromosomes DNA condensed, wrapped around proteins, called histones Nucleus Only visible during cell division Each organism has its own number Corn – 20, fruit fly 8, horsetail – 216, Chimp – 48, Dog – 78, humans? Somatic cells? Sex Cells?  Haploid-half set of chromosomes  23 in our nucleus  Diploid – Full Set of chromosomes  46 in our nucleus

8. Chromosomes  Sister Chromatids  The 2 halves of a replicated chromosome  Centromere  The place where sister chromatids are connected

10. CELL DIVISION

11. Cell Division  Why?  Replace lost cells  Repair  Growth and development  Reproduction

12. Cell Cycle  “ALL CELLS COME FROM CELLS”  The “life cycle” of a cell from the beginning of one division to the beginning of the next division.  Cell division  1 cell becomes 2 The 2 new cells are called Daughter Cells

13. The Cell Cycle  Interphase G1 – primary growth S – DNA replication G2 – Cell carries out everyday functions, prepares for division  Mitosis M – Cell divides  Cytokinesis Cytoplasm divides

14. MITOSIS The Break Down

15. The Phases  Prophase  Metaphase  Anaphase  Telophase  Cytokinesis

16. Prophase  Nucleus disappears  Chromatin condenses forming chromosomes (visible)  Centrioles move to opposite sides of the nucleus  Spindle fibers form between them – some of which attach to centromeres on each side of the chromosome

19. Metaphase  Chromosomes line up in the middle of the cell

22. Anaphase  Sister chromatids split at centromeres to make separate chromosomes  Chromosomes move to opposite ends of the cell

25. Telophase  Chromosomes begin to uncoil back into chromatin  Nuclear membranes develop around the bundles of chromatin at opposite ends of the cell  Spindle fibers disappear  Nucleolus reappear in each new, daughter cell

28. Cytokinesis  When the cytoplasm divides, cell division is complete.

31. Not always the same!  Animals  Cell membrane pinches, forming 2 identical daughter cells  Complete cells that are identical  Plants  Cell Plate forms halfway between the 2 nuclei  Materials for new cell walls and membranes gather and fuse in the middle between the 2 nuclei. Material gradually divides to create 2 cells.