2. After viewing this program you will be able to è Name the major phases of a cell’s life cycle. è Describe the primary characteristics involved in each phase of a cell’s life.

3. Cell Division: The Formation of New Cells

4. Cell Division In order for the total number of cells to increase and for an organism to grow, the cells must undergo cell division.

5. Parent and Daughter Cells During cell division, one cell divides into two cells. Each new cell, called a daughter cell is identical to the parent cell.

6. Stages of Development The life cycle of a cell is divided into a series of stages or phases

7. Interphase The phase in which the cell spends the majority of its life. During this phase, the cell is performing its normal life functions.

8. Interphase Example Red Blood Cells  carrying oxygen

9. Interphase The cell is also preparing for division by replicating its DNA and increasing its size. The cells chromosomes appear in a tangled form known as chromatin. Chromatin

10. Mitosis The actual process of cell division is divided into 4 steps or phases. Prophase Metaphase Anaphase Telophase

11. Prophase Chromatin appears as rodlike bodies known as chromosomes in the nucleus. Each chromosome has made a copy of itself.

12. Prophase These chromosomes are called sister chromatids and are joined by a central part called a centromere.

13. Prophase During this phase a spindle begins to form a “bridge” between opposite ends of the cell. Near the end of this phase, the nuclear membrane and nucleolus also begin to disappear from view.

14. Metaphase The chromosomes prepare for division by lining up along a center line of the cell, referred to as the equator. They are attached to the spindles by their centromeres.

15. Anaphase The chromosomes divide at the centromere and allows the sister chromatids to separate from one another.

16. Telophase The chromosomes reach the opposite ends of the cell. The nuclear membrane and nucleolus begin to reappear.

17. Cytokinesis The cytoplasm is pinched off and divided into two nearly equal parts. Each part contains a nucleus with identical chromosomes. A new cell membrane and in plant cells, a cell wall also forms around the two new cells.

18. Interphase Returns The process of cell division is now over. Two daughter cells have formed, each having the same number and kind of chromosomes as the original parent cell.

19. Chromosome number The number of chromosomes in any organism varies from species to species.

20. Interphase In multicellular organisms such as humans, cell divisions take place millions of times as an organism grows and develops or replaces dead or injured cells. The cell returns to the phase before cell division. It is busy performing its normal duties and making copies of DNA available for the next time it will divide.

21. Mitosis and Cytokinesis Although cell division is broken down into the steps previously discussed, it really occurs in a smooth, continuous process. Double click to watch as the entire process unfolds.

22. Quiz Yourself click on an answer to check 1. The first stage of mitosis when chromosomes become visible is called.. A. anaphase B. prophase C. telophase D. metaphase

23. Sorry, please review Metaphase…... The chromosomes prepare for division by lining up along a center line of the cell, referred to as the equator. They are attached to the spindles by their centromeres. go back

24. Sorry, please review Telophase... The chromosomes reach the opposite ends of the cell. The nuclear membrane and nucleolus begin to reappear. go back

25. Sorry, please review Anaphase... The chromosomes divide at the centromere and allows the sister chromatids to separate from one another. go back

26. CORRECT ANSWER !! Next question

27. Quiz click on the correct answer 2.Which of the following statements is NOT true about mitosis. A. A single cell produces 2 identical daughter cells B. The centromeres divide at Anaphase C. Interphase is the shortest portion of a cell’s life cycle

28. CORRECT ANSWER !! Next question

29. Oops, please review… Parent/Daughter cells go back During cell division, one cell divides into two cells. Each new cell, called a daughter cell is identical to the parent cell.

30. Oops, please review Anaphase... The chromosomes divide at the centromere and allows the sister chromatids to separate from one another. go back

31. Quiz Click on the correct answer 3. During interphase, which of the following occur ? A. The chromosomes appear as chromatin B. The cell increases its size C. The cell is performing its normal life functions D. All of the above

32. CORRECT ANSWER !! Next question

33. NICE TRY !! Review the other parts of Interphase The cell is also preparing for division by replicating its DNA and increasing its size. The cells chromosomes appear in a tangled form known as chromatin. Chromatin go back

34. NICE TRY !! Review the other parts of Interphase go back

35. Quiz Click on the correct answer 4. The four phases of mitosis occur in the following order… A. metaphase, prophase, telophase, anaphase B. prophase, metaphase, telophase, anaphase C. anaphase, prophase, metaphase, telophase D. prophase, metaphase, anaphase, telophase

36. CORRECT ANSWER !! Good Job- Thanks for taking the time to review Cell Division Return to tutorial

37. Uh oh, please review Mitosis The actual process of Mitosis is divided into four steps or phases Prophase Metaphase Anaphase Telophase go back