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Cell division

Cell division . Biology 106. Outline. - Types of cell division - Mitosis Phases of mitosis Diagram shows how mitosis works - Meiosis Phases of meiosis Diagram shows how meiosis works. Mitosis. - This type of cell division allows multicellular organism to grow and repair damage tissue.

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Cell division

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  1. Cell division Biology 106

  2. Outline • - Types of cell division • - Mitosis • Phases of mitosis • Diagram shows how mitosis works • - Meiosis • Phases of meiosis • Diagram shows how meiosis works

  3. Mitosis • - This type of cell division allows multicellular organism to grow and repair damage tissue. • - Mitosis produce two daughter cells that are identical to the parent cell.

  4. Mitosis subdivided into 5 phases • Interphase: takes about 90% of the cell cycle • The cell can grow and copy its chromosomes. • 1- Prophase • 2-Prometaphase • 3-Metaphase • 4-Anaphase • 5-Telophase • Cytokinasis

  5. 1- Prophase -Chromosome condensed and become shorter -Nucleoli disappear -The centrosomes duplicate and mitotic spindle fibers begin to form. • 2-Prometaphase -The nuclear envelope fragmented. -The chromosomes become shorter and attached to spindle fibers.

  6. 3-Metaphase • The centrosomes are at the opposite poles of the cell. • The chromosomes arranged on the metaphase plate. • 4-Anaphase • Tow sister chromatids are separated. • Chromatids moving toward the opposite poles

  7. 5-Telophase • Tow daughter nuclei are formed • Nuclear envelope arises • Chromosomes become less condensed. • Spindle fibers disappear • Cytokinesis: Cytoplasm begins to divide in order to give tow daughter cells that have the same number of chromosomes and genetically identical to the mother cells.

  8. Mitosis

  9. Meiosis • Enable the organisms to reproduce sexually. • Occurs only in the gonad (Ovary & testis) • Gives rise to male and female gametes. • Involves tow nuclear division producing 4 daughter cells.

  10. Meiosis Meiosis I • (Reduction division) 1- Prophase I 2- metaphase I 3- Anaphase I 4- Telophase I • Cytokinesis Meiosis II • (Mitotic division) - See mitotic division

  11. Meiosis I(Reduction division) 1- Prophase I A)Chromosomes condensed & become shorter. B)Disappearance of nucleolus & nuclear envelope C)Formation of spindle fibers D)Homologues pairs of chrmosomes are united together E)Crossing over occures….

  12. 2- metaphase I • Pair of homologues chromosomes arrange at equator (Metaphase plate) • Chromosomes attach to the spindle fibers. • 3- Anaphase I - Separation of homologues pairs of chrmosomes. • 4- Telophase I • Nucleolus & nuclear membranes reappear. • Spindle fiber disappear.

  13. Cytokinesis : • Occurs by dividing the cell into tow daughter cells. • The producing cells have half chromosomal of mother cells and differ genetically from them

  14. Mitosis vs meiosis

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