The Cell Cycle (Somatic Cells)

1. The Cell Cycle(Somatic Cells)

2. Vocabulary • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

3. The Cell Cycle for Somatic Cells • All cells come from cells. To grow and divide (how new cells are made) cells undergo an orderly sequence of events. • First, a cell must copy its DNA (in its chromosomes). • The DNA copies must separate into two sides of the cell. • The cell then splits into 2 identical cells. • So…one skin cell divides into two skin cells, one bone cell divides into two bone cells, one muscle cell divides into two muscle cells, etc.

4. Mitosis: • The part of the cell cycle in which the nucleus divides to form two identical nuclei.

5. Interphase(occurs just before Mitosis begins) Chromatin -(loose threads of DNA in the nucleus of a cell) • The cell grows in size. • DNA (in the chromatin) and organelles (such as centrioles) are replicated (copied). • The cell prepares for division. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

6. Animal cell Plant cell Interphase Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

7. 1st step in Mitosis:Prophase (preparation phase) • The chromatin (duplicated DNA) coils and condenses into chromosomes. • The nuclear membrane disappears. • The spindle fibers begin to form. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

8. Mitosis Prophase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

9. 2nd step in Mitosis:metaphase (organizational phase) • The chromosomes line up in the middle of the cell. • The spindle fibers attach to the centromere of each replicated chromosome. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

10. Mitosis Metaphase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

11. 3rd step in Mitosis:Anaphase (separation phase) • The chromosomes split in the middle and the sister chromatids are pulled by the spindle fibers to opposite sides of the cell. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

12. Plant cell Mitosis Anaphase Animal cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

13. 4th step in Mitosis:Telophase The chromosomes, along with the cytoplasm and its organelles and membranes are divided into 2 portions. This diagram shows the end of telophase. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

14. Mitosis Telophase Animal cell Plant cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

15. After Mitosis:Cytokinesis The actual splitting of the daughter cells into two separate cells is called cytokinesis and occurs differently in both plant and animal Cells. Beginning of cytokinesis in a plant: Beginning of cytokinesis in an animal: http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

16. Meiosis Vocabulary • Diploid Cells – have pairs of similar chromosomes. • Somatic Cells – are diploid cells. • Haploid Cells – do NOT have pairs of chromosomes (have HALF the number of chromosomes that somatic cells have). • Gametes – are haploid sex cells.

17. Meiosis is the process of cell division that results in gametes(sex cells, sperm and egg). • Gametes (haploid number of chromosomes) are needed for sexual reproduction. • In sexual reproduction, the new organism gets half of its chromosomes from one parent (mother via the egg)and half from another parent (father via the sperm).

19. Before Meiosis:Interphase The chromosomes have replicated, and the chromatin begins to condense. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

20. Meiosis Prophase I • The chromosomes are completely condensed. • In meiosis (unlike mitosis), the homologous chromosome pairs join together. • While the homologous chromosomes are joined, they exchange DNA (called crossing over). http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

21. Meiosis Metaphase I The nuclear membrane dissolves and the homologous chromosomes attach to the spindle fibers. They are preparing to go to opposite poles. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

22. Meiosis Anaphase I The chromosomes move to opposite ends of the cell. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

23. Meiosis Telophase I & Cytokinesis • The cell begins to divide into two daughter cells. It is important to understand that each daughter cell can get any combination of maternal orpaternal chromosomes. • So…the daughter cells are NOT identical copies of each other (unlike mitosis). http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

24. Meiosis Prophase II The cell has divided into two daughter cells. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

25. Meiosis Metaphase II As in Meiosis I, the chromosomes line up on the spindle fibers. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

26. Meiosis Anaphase II • The two cells each begin to divide. • The chromosomes separate and the sister chromatids move to opposite ends of each cell. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

27. Telophase II &Cytokinesis With the formation of four cells, meiosis is over. Each of these prospective germ cells carries half the number of chromosomes of somatic cells. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

28. For Example:

29. This may you remember these terms: • MITosis takes the cell and Makes It Two (diploid) • Meiosis has to do with sexual reproduction • Meiosis results in an egg or sperm. Clyde Freeman Herreid – Dept. of Biological Sciences: Buffalo State Univ. of New York