1. What do you want to be when you grow up???

2. Cell Differentiation Zygotes (sperm + egg) first divide into embryonic stem cells. Stem cells develop in two stages. –Determination-cells commit to become one cell type –Differentiation-cells acquire specialized structures and functions of highly specialized cells Specific genes are turned on and off

4. Quick Question… How does the process of cell determination differ from the process of cell differentiation?

5. Cell Cycle & Mitosis Chapter 5

6. Hmm… Why do you have to keep cutting your fingernails….grass……hair??

7. Cell cycle has 3 main phases

8. Cell Cycle G1 phaseS phase G2 phase The cell growsThe DNA replicatesThe cell prepares to divide INTERPHASE

9. Parts of the Cell Cycle A.Interphase – Growth period of the cell. Consists of 3 phases: 1.G1 = Rapid growth and metabolic activity (production of organelles) 2.S = DNA synthesis (replication) 3.G2 = Growth and protein synthesis (centrioles replicate)

11. G1 or gap 1 phase in which daughter cells are growing and carrying out their normal functions (example: skeletal muscle cells-contract and joints move) the cells are 2n and 2c (they are diploid and have 2 copies of each of the chromosomes)

12. S phase or synthesis DNA replication occurs, making duplicate copies of each of the chromosomes in preparation for cell division (each chromosome consists of 2 sister chromatids which are tightly bound to each other) the cells are 2n and 4c (they are diploid, but have 4 copies of each chromosome)

13. A Chromosome

14. Chromosome Chromosome-one long continuous thread of DNA that consists of numerous genes along with regulatory information

15. G2 or gap 2 the cells may grow more at this point at the end of G2, chromosomes begin to condense in preparation for cell division

16. Interphase

17. the "holding" stage or the stage between two successive cell divisions. Some 90% of a cell's time in the normal cellular cycle may be spent in this phase C= chromatin I = nucleolus

19. Mitosis ProphaseMetaphaseAnaphaseTelophase M Phase

20. 2 processes involved in Division –Mitosis-division of cell nucleus and its contents –Cytokinesis-process that divides the cell cytoplasm –Result of mitosis is two daughter cells that are genetically identical to the original

21. Cells divide at different rates Prokaryotes typically divide faster because they do not have membrane bound organelles and cytoskeleton

22. Prophase The nuclear membrane breaks down and the chromosomes become short and thick. By late prophase, individual chromosomes are visible, appearing as two parallel threads attached at a constriction point called the centromere.

23. Prophase the chromatin condenses into discrete chromosomes. The nuclear envelope breaks down and spindles begin to move to the opposite "poles" of the cell.

24. Prophase

26. Metaphase The spindle fibers attach to each chromosome on either side of its centromere. The spindle fibers force the chromosomes into a tight plane which is a circle around the middle of the cell

27. Metaphase the nuclear membrane disappears completely. The spindle fully develops and the chromosomes align at the metaphase plate (a plane that is equally distant from the two spindle poles).spindle Ch= chromosome S= spindle

29. Metaphase

30. Anaphase Anaphase is the shortest stage of mitosis and is the separation of the chromosomes. The chromatids that were attached to the same centromere now separate and move to opposite poles of the spindle. The chromosome arms from a “V” as they are dragged through the cytoplasm. By the end of anaphase, chromosomes have been separated into two genetically identical nuclei.

31. Anaphase the paired chromosomes (sister chromatids) separate. Spindle fibers attached to the sister chromatids shorten and begin moving them to opposite ends (poles)

33. Anaphase

34. Early Telophase nuclei begin to form at opposite poles. Cytokinesis, the division of the original cell's cytoplasm, also begins. In plants, the cell begins to form a cell wall.

35. Late Telophase the chromosomes are cordoned off in distinct new nuclei in the emerging daughter cells. daughter cells The division of the original cell's cytoplasm is called cytokinesis

36. Telophase Telophase is prophase in reverse. The spindle fibers disappear, a nuclear membrane forms around each of the two sets of chromosomes, and a nucleoli appears in each new nucleus. The chromosomes become longer.

38. Telophase

39. Cytokinesis Cytokinesis splits the cytoplasm of dividing cell into daughter cells.

40. Cytokinesis

41. Can you identify?

43. What phase?

45. Name that phase!

47. Onion Root Tip

49. Onion Root tip