1. Friday Feb 10 th Day E Collect remaining Wequests Begin 10.2 –Notes –Video Clip –Handout HW – Study for 10.1 Quiz Chapter 10 Vocabulary Surface area/volume problems

2. Chapter 10.2 Cell Division

3. Before a cell gets too large, a growing cell divides forming two “daughter cells” Cell division  process by which a cell divides into two new daughter cells Before cell division begins,  DNA replicates (copies) itself  One copy for each new cell

4. Division in Prokaryotes After DNA is copied, cell splits in two binary fission  Each new cell contains a copy of the DNA called binary fission –Example of  asexual reproduction Binary Fission in a Paramecium

5. Division in Eukaryotes Occurs in two main stages –1 st stage  division of the nucleus = mitosis –2 nd stage  division of the cytoplasm = cytokinesis Helps multicellular organisms  grow and develop

6. Chromosomes  Structures that carry genetic information –Made up of  DNA and protein (histones) Humans have  46 total (23 pairs) (other organisms have different numbers)

8. Chromosomes While the cell is “resting”, you cannot see the chromosomes.  It is unwound  Called chromatin chromatin chromosome (1) Double-stranded DNA. (2) Chromatin strand (DNA with histones). (3) Chromatin during interphase with centromere. (4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (5) Chromosome during metaphase.

9. Chromosomes While the cell is dividing, you can see the chromosomes  It is wound up  Made of two sister chromatids connected by a centromere

10. Chromosomes Centromere Sister Chromatid

11. The Cell Cycle Occurs in  eukaryotic cells  It is the period of time from the beginning of one cell division to the beginning of the next Cell doubles its contents so that it is ready to divide into two completely independent cells M phase S phase G 1 phase G 2 phase

12. The Cell Cycle Consists of 4 phases –1. M phase – mitosis  the division of the cell nucleus and cytokinesis –2. G1  intense growth and activity; new proteins and organelles are made –3. S phase  copying of chromosomes –4. G2  intense growth and activity; new proteins and organelles are made Shortest of the four phases M phase S phase G 1 phase G 2 phase

13. M phase Cell division daughter cells –Process in which the cell divides into two independent cells  daughter cells mitosis binary fission –Process is called  mitosis in eukaryotes and  binary fission in prokaryotes

14. Cell Cycle Rates  Cells do not move through the cell cycle at the same rate –Average rate of a human cell is once every 20 hours

15. Mitosis Time of cell division Divided into four main phases –1. Prophase –2. Metaphase –3. Anaphase –4. Telophase

16. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

17. 1. Prophase 1. Appearance of chromosomes –2 sister chromatids attached at the centromere 2. Nuclear membrane begins to breakdown 3. Spindle begins to form –Purpose is to pull chromatids apart 4. Spindle attaches to the chromosomes at the centromere –In animals, spindle is made by the centriole  Plants lack centrioles Spindle forming Centromere Chromosomes (paired chromatids)

18. 2. Metaphase 1. Chromosomes line up in the middle of the cell Centriole Spindle

19. 3. Anaphase 1. Centromeres split 2. Sister chromatids are pulled to the opposite ends of the cell by the spindle Individual chromosomes

20. 4. Telophase 1. Spindle breaks down 2. Nuclear envelope reforms around the chromosomes 3. Chromosomes unwind to chromatin again Nuclear envelope reforming

21. Cytokinesis Division of the cytoplasm In animals  the cell pinches in at the middle to create two new cells In plants  a cell plate is created in the middle of the cell

22. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Centriole Chromosomes (paired chromatids) Prophase Centromere Spindle forming Section 10-2 Mitosis and Cytokinesis

23. Videos Animal Cell Mitosis Animal Cell Cytokinesis Animal Cell Mitosis: Interactive How the Cell Cycle Works

24. Friday Feb 10 th Day E Collect remaining Wequests Begin 10.2 –Notes –Video Clip –Handout HW – Study for 10.1 Quiz Chapter 10 Vocabulary Surface area/volume problems