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นำเสนอโดย… นำงศิณีวณ ั ย์ พิทกั ษ์ทิม D5010264 นำยอภัย ดวงคำ M5010288 นำงสำววณัทกมล นำคณรงค์ M5010042 จะบอกให้นะ ก็คอื เซลล์ขนาดเล็กมีพ้ นื ที่ผิวต่อปริมาตรเป็ น อย่างไรนะ? มีความสาคัญอย่างไร การเพิ่มจานวนเซลล์มีผลต่อ สิง่ มีชีวติ อย่างไรบ้าง ? มีโครโมโซมเป็ น 2n ( Diploid ) มีโครโมโซมเป็ น n ( Haploid ) กระบวนกำรเพิ่มจำนวน ของเซลล์มีกระบวนกำร อย่ำงไรบ้ำงนะ?? Duplication of the chromosome Continued growth of the cell Division into two cells Rod-Shaped Bacterium, E. coli, dividing by binary fission Interphase Mitotic phase / M phase เพื่อเพิ่มจำนวนเซลล์ ร่ำงกำย (Somatic cell) พบในสิ่งมีชีวติ ชัน้ สูง เช่ น พืช สัตว์ เป็ นกำรแบ่ งเซลล์ เพื่อกำรสืบพันธุ์ของ สิ่งมีชีวิตบำงชนิด (Haploid/ Monploid) The stage of mitosis division Mitosis Cytokinesis Cellular metabolic activity is high , chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the time of each cell cycle. G1 phase S phase G2 phase G1 Phase: Growth--the cell grows in size. S Phase : Prior to mitosis, the cell readies itself by duplicating its chromosomes and other cellular contents. - Before DNA synthesis, the cell’s chromosomes consist of one chromatid. - After DNA synthesis, the cell’s chromosomes consist of dyads with 2 identical sister chromatids attached at the centromere. G2 Phase : The cell prepares the enzymes and machinery for mitosis Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase Cytokinesis G1 phase S phase G2 phase Mitosis - Chromatin Chromosome (two sister chromatids) - Nuclear envelope breaks into fragments. - Microtublues Mitotic spindle. - Some of the spindle fibers reach the chromosomes and attachit. - Nonkinetochore microtubules overlap with those coming from the opposite pole The chromosomes align at the equitorial plate and are held in place by microtubules attached to the mitotic spindle and to part of the centromere. During anaphase the mitotic spindle apparatus pulls the chromatids of each chromosome apart by attaching to each centromere. Note that the telomeres of each chromosome point toward the cell’s equator. Chromosomes begin to disperse. Spindle fibers disperse. The nuclear envelope forms again around the nuclei. Cytokinesis begins--formation of daughter cells. In animals, like the whitefish, a cleavage furrow, a contractile ring of muscle like fibers, pinches the cell into two. Meiosis Sexual reproduction occurs only in eukaryotes. During the formation of gametes, the number of chromosomes is reduced by half, and returned to the full amount when the two gametes fuse during fertilization. Meiosis is a cell division process in organisms that sexually reproduce. Human Life Cycle Phases of Meiosis meiosis I meiosis II Phases of Meiosis Interphase Meiosis II Meiosis I Prophase II Prophase I Metaphase II Metaphase I Anaphase I Anaphase II Telophase I Telophase II Crossing Over Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Johnson - The Living World: 3rd Ed. - All Rights Reserved - McGraw Hill Companies Comparison of Mitosis and Meiosis THANK YOU