CHAPTER 8 Cellular Reproduction: Cells from Cells
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings MITOSIS Before a parent cell divides, it duplicates its chromosomes. The two resulting “daughter” cells are genetically identical. Cell division plays a role in –The replacement of lost or damaged cells. –Cell reproduction and growth.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Reproduction of Organisms In asexual reproduction, single-celled organisms reproduce by simple cell division. Hydra Budding
Figure 8.2a
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings –Some multicellular organisms can divide into pieces that then grow into new individuals.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Sexual reproduction is different. –It requires fertilization of an egg by a sperm. –Production of egg and sperm is called meiosis. LATER
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Almost all of the genes of a eukaryotic cell –Are located on chromosomes in the cell nucleus. –Mitochondia and Chloroplast have some The Cell Cycle and Mitosis
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Eukaryotic Chromosomes Each eukaryotic chromosome contains one very long DNA molecule, –Typically bearing thousands of genes. The number of chromosomes in a eukaryotic cell –Depends on the species.
Figure 8.3
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings HUMANS HAVE 46 Chromosomes –Are made of chromatin, a combination of DNA and protein molecules. –Are not visible in a cell until cell division occurs.
Figure 8.4
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding. DNA Packing
Figure 8.5
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Before a cell divides, it duplicates all of its chromosomes, resulting in two copies called sister chromatids.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings When the cell divides, the sister chromatids separate from each other. Mitosis Overview Late Interphase Prophase Prometaphase Metaphase Anaphase Telophase
Figure 8.6
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Cell Cycle Eukaryotic cells that divide undergo an orderly sequence of events called the cell cycle. The cell cycle consists of two distinct phases: –Interphase –Mitotic phase WHY ARE WE DIVIDING THE CELL????
Figure 8.7
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mitosis and Cytokinesis Mitosis –Is the division of the chromosomes. –Is preceded by interphase. Mitosis (All Phases) Animal Mitosis Sea Urchin (time lapse)
Figure 8.8.1
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mitosis consists of four distinct phases: –Prophase –Metaphase
Figure 8.8.2
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings –Anaphase –Telophase
Figure 8.8.3
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cytokinesis –Typically occurs during telophase. –Is the division of the cytoplasm. –Is different in plant and animal cells. Cytokinesis
Figure 8.9a
Figure 8.9b
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cancer Cells: Growing Out of Control Normal plant and animal cells have a cell cycle control system. What Is Cancer? Cancer is a disease of the cell cycle. Cancer cells do not respond normally to the cell cycle control system. Cancer cells can form tumors, –Abnormally growing masses of body cells. If a tumor is malignant, –It can spread to other parts of the body.
Figure 8.10
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cancer Treatment Cancer treatment can involve –Radiation therapy, which damages DNA and disrupts cell division. –Chemotherapy, which uses drugs that disrupt cell division.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Cancer Prevention and Survival Cancer prevention includes changes in lifestyle: –Not smoking –Exercising adequately –Avoiding exposure to the sun –Eating a high-fiber, low-fat diet –Visiting the doctor regularly –Performing regular self-examinations