1. Mitosis Overview

2. Objectives Name and describe the two types of reproduction. Explain what happens during the cell cycle. Explain what happens in the stages of mitosis. Discuss how mitotic cell division in unicellular and multicellular organisms are controlled.

3. Terms to know: - mitosis -cytokinesis -interphase -prophase -metaphase -anaphase -telophase -cell cycle -asexual reproduction -chromosomes -sexual reproduction -binary fission -budding -spores -gametes -chromatin

4. Why must cells divide: Cells must divide in order for an organism to be able to: Grow Maintain and repair body tissues Reproduce

5. Function of mitotic cell division Mitosis is important for the growth, maintenance, repair, reproduction of eukaryotic body cells. Kidney, liver, skin, heart, pancreas cells etc. all reproduce by mitotic cell divisions. Mitosis results in 2 daughter cells that have the exact same DNA as the mother cells.

6. Two major types of reproduction 1.Asexual reproduction: Only 1 parent organism reproduces by itself, no sex cells are involved. Offspring are genetically identical to parent. 2.Sexual reproduction: Two parent organisms reproduce to form a new organism. Gametes or sex cells (sperm and egg) are involved. Offspring are contains genes from both parents.

7. Two types of reproduction: Asexual reproduction occurs in single celled organisms, some plants, and some animals. Sexual reproduction occurs in most animals and plants.

8. Cell Division Before it becomes too large, a growing cell must divide forming two daughter cells. The process by which a cell divides into two new daughter cells is called cell division.

9. Cell Division Before cell division occurs, the cell replicates, or copies, all of its DNA. This replication of DNA solves the problem of information storage because each new daughter cell gets one complete set of genetic information. Thus, each daughter cell now contains its own genetic “library”.

10. The cell cycle and mitosis During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells each of which then begins the cycle again. Mitosis: A process of the cell cycle that occurs when a cell with a distinct nucleus divides to form two daughter cells.

11. 5 Phases of the cell cycle 1.The cell grows and develops (G 1 ) 2.The genetic material is replicated inside the parent cell (S) 3.The cell continues to grow and develop (G 2 ) 4.The nucleus divides in two separating the genetic material into two equal parts (mitosis) 5.The cytoplasm divides forming two new daughter cells (cytokinesis)

12. Cell cycle and mitosis

13. Questions: 1.What does the nucleus contain and why must it divide? 2.What kinds of cells can undergo mitosis? (eukaryotic or prokaryotic)

14. Mitosis and changes in the nucleus DNA is the genetic information needed to make important cell structures. It also determines how the organism will look, behave, and function. Before a cell divides, the DNA must be replicated so that each new daughter cell has a copy of the information.

15. Mitosis and changes in the nucleus Before the cell divides, the DNA in the nucleus appears as loose fibers called chromatin. Before mitosis begins, the DNA must be replicated. As the cell enters mitosis, the chromatin coils up into structure called chromosomes.

16. Mitosis and changes in the nucleus Imagine: Each strand of DNA within each of your cells is about 6 feet long. The DNA becomes so tightly coiled into the chromosomes that it can actually fit into a microscopic cell!! Humans have 46 chromosomes in each of our body cells.

17. What exactly is a chromosome? Chromosomes are composed of tightly coiled DNA and proteins called histones, which allow the DNA to coil into these compact structures. Chromosomes contain genes which code for various traits.

18. Chromatid

19. Mitosis and changes in the nucleus During cell division, before mitosis, it is the chromosomes that duplicate. Why must the chromosomes duplicate before mitosis?

20. Interphase and Mitosis When a cell is not dividing, it is in interphase. During interphase the cell: –Grows in size –Replicates its chromosomes (they double in number) –Metabolic activity is at its highest

21. Mitosis –Division of the nucleus Mitosis involve 4 phases. 1.Prophase: 2.Metaphase: 3.Anaphase: 4.Telophase: Plainedge Made A Touchdown

22. Prophase The chromatin thickens and coils into chromosomes The nuclear membrane disappears Mitotic spindle fibers form from centrioles

23. Metaphase Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is called the metaphase plate. This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome.

24. Anaphase The paired chromosomes separate at the kinetochores and move to opposite sides of the cell. Kinetochore: part of chromosomes where spindle fiber attaches Motion results from a combination of kinetochore movement along the spindle microtubules

25. Kinetochore and Spindle Microtubules

26. Telophase Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope. The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage.

27. Cytokinesis In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus. In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.

28. Whitefish Mitosis interphase metaphase prophase anaphasetelophase

29. What Phase is this? Prophase Nuclear membrane is gone. DNA condensed into chromosomes

30. How about this? Anaphase Chromosomes are being pulled apart to opposite ends of the cell.

31. What Phase is this? Telophase Nuclear membrane has reappeared DNA is now in chromatin form. Cell membrane pinches cell into 2 new daughter cells.

32. What Phase is this? Metaphase Chromosomes are lined up in the center of the cell. Spindle fiber network is visible

33. What Phase is this? Interphase Nuclear membrane is visible DNA in form of chromatin.

34. Related Websites http://www.cellsalive.com/mitosis.htm http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.htmlhttp://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.html http://www.sci.sdsu.edu/multimedia/mitosis/ http://biologyinmotion.com/cell_division/ http://www.life.umd.edu/CBMG/faculty/wolniak/wolniak mitosis.htmlhttp://www.life.umd.edu/CBMG/faculty/wolniak/wolniak mitosis.html http://www.bio.unc.edu/faculty/salmon/lab/mitosis/mitosi s.htmlhttp://www.bio.unc.edu/faculty/salmon/lab/mitosis/mitosi s.html