Copyright Pearson Prentice Hall 10-2 Cell Division Photo Credit: © CAMR/A.B. Dowsett/Science Photo Library/Photo Researchers, Inc. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Sister chromatids Centromere Chromosomes Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. Video of this Photo Credit: © Gunther F. Bahr/AFIP/Stone Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Cell Cycle The cell cycle consists of four phases: G1 (First Gap Phase) S Phase G2 (Second Gap Phase) M Phase (cell division) Mitosis (Prophase, Metaphase, Anaphase, Telophase) Cytokinesis INTERPHASE Copyright Pearson Prentice Hall

Events of the Cell Cycle During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases. Copyright Pearson Prentice Hall

Events of the Cell Cycle During G1, the cell increases in size synthesizes new proteins and organelles During the S phase, chromosomes are replicated DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle. The G2 Phase (Second Gap Phase) organelles and molecules required for cell division are produced Once G2 is complete, the cell is ready to start the M phase—Mitosis Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Mitosis Biologists divide the events of mitosis into four phases: Prophase Metaphase Anaphase Telophase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Movie Time & LAB TIME!!!! Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells. Mitosis Copyright Pearson Prentice Hall

Chromosomes (paired chromatids) Mitosis Section 10-2 Spindle forming Prophase Prophase Chromosomes (paired chromatids) Centromere Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells. Click to Continue Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Spindle forming Prophase Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Centromere Chromosomes (paired chromatids) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Spindle forming The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Centromere Chromosomes (paired chromatids) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Spindle forming Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Centromere Chromosomes (paired chromatids) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Metaphase Centriole Spindle Centriole Metaphase Click to Continue Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Centriole Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Spindle Copyright Pearson Prentice Hall

Individual chromosomes Mitosis Anaphase Individual chromosomes Anaphase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Anaphase Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Individual chromosomes Copyright Pearson Prentice Hall

Nuclear envelope reforming Mitosis Telophase Nuclear envelope reforming Telophase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis A new nuclear envelope forms around each cluster of chromosomes. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cytokinesis Cytokinesis Cytokinesis Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cytokinesis During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cytokinesis in Plants In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell plate Cell wall Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cytokinesis in Plants The cell plate gradually develops into a separating membrane. A cell wall then begins to appear in the cell plate. Copyright Pearson Prentice Hall