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Major Objectives 1. What are the two key roles of mitotic cell division? 2. Understand the different phases of the mitotic cell cycle and the regulation of the cell cycle (checkpoints) 3. Understand the phases of mitosis 4. Know how cytokinesis differs between plant and animal cells Two key roles of mitotic cell division 1. Cell division functions in reproduction, growth, and repair 2. Cell division distributes identical sets of chromosomes to daughter cells Mitotic Cell Cycle Interphase (4 subphases) G0) Phase-Cell leaves cell cycle. G1 Phase-Centered on growth. Cells increase in size, produce RNA and synthesize protein. (G1 Checkpoint) ensures that everything is ready for DNA synthesis. Interphase (4 subphases) S Phase Synthesis-chromosomes copied. ·To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs Interphase (4 subphases) G2 Phase-Second Gap Phase. Cell completes preparations for cell division. ·Cell will continue to grow and produce new proteins. (G2 Checkpoint) to determine if the cell can now proceed to enter M (mitosis) and divide. Mitosis or M Phase: Cell growth and protein production stop at this stage in the cell cycle. Division into two similar daughter cells. (Metaphase Checkpoint) that ensures the cell is ready to complete cell division. Normal Cells vs Cancer Cells http://www.youtube.com/watch?v=8LhQllh46yI Cytokinesis -Division of the cytoplasm after mitosis Animals-Cleavage furrow in the cell surface forms and the ring pinches the cell in two Plants-Cell plate is formed during telophase and the plate enlarges until its membranes fuse with plasma membrane Mitosis in PlantsA review Plant Interphase Cell prepares for division by: •replicating DNA and organelles •increasing cell size Plant Prophase Cell prepares for nuclear division by: •condensing DNA into movable packages called chromosomes Plant Metaphase Cell prepares chromosomes for division by: •aligning chromosomes at cell equator •attaching spindle fibers from each new daughter cell pole to each chromosome at the centromere Plant Anaphase Chromosomes divide: •spindle fibers pull chromosomes apart •one-half of each chromosome (chromatid) moves to a new daughter cell Plant Telophase Cytoplasm divides: •DNA de-condenses and two nuclei form •new cell wall (cell plate) appears between the two nuclei to form two new daughter cells Mitosis in AnimalsA review Prophase Double chromatin chromosomes present and nuclear envelope disappears Metaphase Double chromatin chromosomes lineup in single file on metaphase equator of the cell Anaphase Centromeres divide and single chromatin chromosomes move towards opposite poles of cell Telophase Cytokinesis begins (cleavage furrow). Nuclear envelope begins to reform around single chromatin chromosomes Cytokinesis Cytokinesis complete, chromosomes disappear, chromatin reforms, and 2 new daughter cells enter G1 phase cell cycle
