The document discusses the process of cell division through mitosis and cytokinesis. It explains that eukaryotic cells undergo a cell cycle that includes interphase, where the cell grows and duplicates its DNA, and the mitotic phase. During mitosis, the cell divides into two daughter cells through four main phases - prophase, metaphase, anaphase and telophase. Cytokinesis then separates the cytoplasmic components of the parent cell. Cancer cells are able to divide uncontrollably due to mutations in cell cycle regulation genes.

1. Cell Division

2. Chromosomes Are made of DNA Each chromosome consists of sister chromatids attached at a centromere

3. Cell Cycle During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each of which then begins the cycle again. Interphase – time for growth and regular cell activity. Most of a cell’s life is spent in Interphase.

4. Interphase

5. Introduction to Cell Division A time when a cell performs its usual functions, depending on the location in the body.

6. Mitosis The division of somatic or regular cells. Its divided into 4 phases. Remember Interphase is NOT part of Mitosis.

7. Introduction to Mitosis

8. Prophase First stage of Mitosis Chromatin condenses into chromosomes Centrioles separate and a spindle fiber begins to form. Nuclear membrane breaks down

9. Prophase

10. Metaphase Second Phase of Mitosis Chromosomes line up in the middle of the cell. Each chromosome is connected to a spindle fiber.

11. Metaphase

12. Anaphase Third Phase of Mitosis The sister chromatids separate into individual chromosomes and move apart to opposite ends of the cell.

13. Anaphase

14. Telophase Fourth and Final Stage of Mitosis Chromosomes gather at opposite ends of the cell and lose their distinct shapes Two new nuclear membranes have formed.

15. Telophase

16. Cytokinesis The cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes

17. Regulating the Cycle A protein called cyclin helps regulate the cell cycle in eukaryotic cells. They respond to internal and external events. These proteins are regulators.

18. When Things Go Wrong Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, they form masses of cells called tumors that can damage surrounding tissues.

19. The Cell Cycle in Depth Interphase Mitotic Stage Cytokinesis Apoptosis Cell Cycle and Cancer

20. INTERPHASE 3 STAGES G 1 stage S Stage G 2 Stage Some cells such as nerve and muscle cells typically do NOT complete the cell cycle and are said to have entered the G 0 stage. For adult mammalian cells, interphase lasts ~20 hours (90% of cell cycle)

21. INTERPHASE: G 1 stage Stage BEFORE DNA replication Cell doubles its organelles and accumulates materials for DNA synthesis G used to stand for “gap” but now it stands for “growth” Protein synthesis is a part of these growth stages

22. INTERPHASE: S stage DNA synthesis/replication occurs Each chromosome is composed of one chromatid (DNA double helix) and makes 2 sister chromatids (2 identical DNA double helix molecules)

23. INTERPHASE: G 2 stage Stage from the completion of DNA replication to the onset of mitosis The cell synthesizes protein that will assist cell division (i.e. protein found in microtubules)

24. M (Mitotic Stage) The cell division stage that includes mitosis (nuclear division) and cytokinesis (division of the cytoplasm)

25. Prophase Nucleolus is disappearing Nuclear envelope is fragmenting Spindle is forming between centrosomes Asters radiate from the centrioles within the centrosomes

26. Prometaphase Kinetochores of sister chromatids attach to kinetochore spindle fibers extending from opposite poles Chromosomes move back and forth until they are aligned at the metaphase plate

27. Metaphase Spindle is fully formed Duplicated chromosomes align at metaphase plate Spindle consists of polar spindle fibers that overlap at the metaphase plate Kinetochore spindle fibers that are attached to chromosomes

28. Anaphase Sister chromatids separate to become daughter chromosomes that move toward the poles Polar spindle fibers slide past one another Kinetochore spindle fibers disassemble Cytokinesis by furrowing begins

29. Telophase Nuclear envelopes re-form Chromosomes begin changing back to chromatin Nucleoli reappear Spindle disappears

30. Plant Cells Lack centrioles and asters Mitotic spindle still forms and goes through the same 5 mitotic phases

31. Cytokinesis In animal cells, it’s a furrowing process that divides the cytoplasm In plant cells, the formation of a cell plate from which the plasma membrane and cell wall are completed

32. The Cell Cycle and Cancer Cancer is due to the mutation of genes that control the cell cycle Cancer cells are… Are Nondifferentiated Divide repeatedly Have abnormal nuclei Don’t require growth factors Not constrained by their neighbors

33. The Cell Cycle and Cancer After forming a tumor, cancer cells metastasize and start new tumors elsewhere in body. What you can do to try to prevent cancer… Avoid unnecessary radiation Avoid exposure to organic chemicals (ex: tobacco smoke) Have a diet rich in fruits and vegetables

34. Prokaryotic Cell Division Prokaryotic chromosome has a few proteins and a single, long loop of DNA Binary fission- the chromosome attaches to the inside of the plasma membrane and replicates. As cell elongates, the chromosomes are pulled apart Inward growth of the plasma membrane and formation of new cell wall material divide the cell in 2.

35. Prokaryotic vs. Eukaryotic Cells Binary fission (in prokaryotes) and mitosis (in cellular eukaryotic protists and fungi) allow organisms to reproduce asexually Mitosis in multicellular eukaryotes is primarily for the purpose of development, growth, and repair of tissues.