Cellular Reproduction

1. Cellular Reproduction 9

2. The Big Idea • Cells go through a life cycle that includes interphase, mitosis, and cytokinesis.

3. Section 9.1: Cellular GrowthMain Idea #1 • Cells grow until they reach their size limit, then they either stop growing or divide.

4. What Limits Cell Size? • As the cell grows, its volume increases much more rapidly than the surface area. • The cell might have difficulty supplying nutrients and expelling enough waste products.

5. What Limits Cell Size? • Transport of Substances • Substances move by diffusion or by motor proteins. • Diffusion over large distances is slow and inefficient. • Small cells maintain more efficient transport systems. • Cell Communication • The need for signaling proteins to move throughout the cell also limits cell size. • Cell size affects the ability of the cell to communicate instructions for cellular functions.

6. The Cell Cycle • Cell division prevents the cell from becoming too large. • It also is the way the cell reproduces so that you grow and heal certain injuries. • Cells reproduce by a cycle of growing and dividing called the cell cycle.

7. The Cell Cycle • Interphase is the stage during which the cell grows, carries out cellular functions, and replicates. • Mitosis is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide. • Cytokinesis is the method by which a cell’s cytoplasm divides, creating a new cell.

8. Interphase • The first stage of interphase, G1 • The cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

9. Interphase • The second stage of Interphase, S • The cell copies its DNA in preparation for cell division.

10. Interphase • The third stage of Interphase, G2 • The cell prepares for the division of its nucleus.

11. Cells Alive • On laptops, go to • Click on Interactive Cell Cycle • Complete Worksheet - “Cells Alive”

12. Section 9.2: Mitosis and CytokinesisMain Idea #2 • Eukaryotic cells reproduce by mitosis, the process of • nuclear division, and cytokinesis, the process of cytoplasm divisions.

13. Cell Division – Intro • Cell division in prokaryotes occurs by binary fission. • A prokaryote cell copies its DNA. • The cell begins to divide. • Two identical haploid cells are produced that contain identical DNA. • Eukaryotic cell division is much more complex; there are two types. • Mitosis - results in new cells with genetic material that is identical to the original cell • Meiosis - reduces the chromosome number by half in the new cells; ex - sex cells

14. Mitosis • Mitosis is the division of the nucleus during cell division. • Mitosis is a continuous process that is divided into four phases: Prophase, Metaphase, Anaphase, Telophase

15. Prophase • DNA begins to shorten and tightly coil into the rod-shaped chromosomes. • The nucleolus and nuclear membrane begin to disappear. • Centrosomes and centrioles begin to appear and start to move to the opposite ends of the cell.

16. Prophase • As the centrosomes separate, spindle fibers begin to form and create a structure known as the mitotic spindle. • The mitotic spindle helps to divide the chromatids into equal halves. • There are two types of fibers within the mitotic spindle: kinetochore and polar fibers.

17. Metaphase • This is the easiest phase to see the chromosomes. • Sister chromatids are pulled along the spindle apparatus toward the center of the cell. • They line up in the middle of the cell.

18. Anaphase • The microtubules of the spindle apparatus begin to shorten. • The sister chromatids separate. • The chromosomes move toward the poles of the cell.

19. Telophase • The chromosomes arrive at the poles and begin to relax. • Two new nuclear membranes begin to form and the nucleoli reappear. • The spindle apparatus disassembles.

20. Cytokinesis • In animal cells, microfilaments constrict, or pinch, the cytoplasm. The part that pinches in and eventually separates is called the cleavage furrow. • In plant cells, a new structure, called a cell plate, forms.

21. Mitosis Internet Lesson • http://www.biologycorner.com/worksheets/mitosis.html#.Unb7qBahClL

22. Section 9.3 Cell Cylce RegulationMain Idea #3 • The normal cell cycle is regulated by cyclin proteins.

23. Abnormal Cell Cycle: Cancer • Cancer is the uncontrolled growth and division of cells. • Cancer cells can kill an organism by crowding out normal cells, resulting in the loss of tissue function.

24. Causes of Cancer • The changes that occur in the regulation of cell growth and division of cancer cells are due to mutations. • Various environmental factors can affect the occurrence of cancer cells. • Factors that can cause cancer are called carcinogens. • Examples include smoke, sunlight, chemicals, radiation, etc.

25. Apoptosis • Apoptosis is programmed cell death. • Cells going through apoptosis actually shrink and shrivel in a controlled process.

26. Stem Cells • Stem cells are unspecialized cells that can develop into specialized cells when under the right conditions. • After fertilization, the resulting mass of cells divides repeatedly until there are about 100–150 cells. These cells have not become specialized. • Adult stem cells are found in various tissues in the body and might be used to maintain and repair the same kind of tissue. • Adult stem cells are less controversial because the adult stem cells can be obtained with the consent of their donor