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Asexual Reproduction & Mitosis Notes

Asexual Reproduction & Mitosis Notes. Asexual Reproduction. Definition: one parent produces genetically identical offspring Advantages: Can produce offspring w/o a mate Many offspring in short time Disadvantages: No variation in offspring No adaptation to new/changing environments.

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Asexual Reproduction & Mitosis Notes

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  1. Asexual Reproduction & MitosisNotes

  2. Asexual Reproduction • Definition: one parent produces genetically identical offspring • Advantages: • Can produce offspring w/o a mate • Many offspring in short time • Disadvantages: • No variation in offspring • No adaptation to new/changing environments

  3. What kinds/types of reproduction are asexual? • Budding - a new individual grows on a ‘parent’ • Example: hydra, yeast Asexual Reproduction

  4. What kinds of reproduction are asexual? 2. Binary Fission - a ‘parent individual’ splits into two independent organisms Example: bacteria Asexual Reproduction

  5. What kinds of reproduction are asexual? 3. Regeneration - fragments of the ‘parent’ can grow into new organisms Example: starfish, planarian Asexual Reproduction

  6. What kinds of reproduction are asexual? Asexual Reproduction 4. Parthenogenesis - production of offspring from unfertilized eggs

  7. What kinds of reproduction are asexual? Asexual Reproduction 5. Vegetative reproduction - occurs in plants New plants rise w/o the production of seeds or spores

  8. Mitosis • Makes two cells that are genetically identical to each other • Purpose? – growth and repair

  9. Chromosomes -passed on from one generation to the next -genetic material composed of genes which are made up of DNA • Only visible during cell division • Found in the nucleus • Condensed DNA

  10. How DNA forms chromosomes

  11. Chromatin • Chromatin – uncondensed DNA; appears very “stringy” • Form of DNA between cell divisions

  12. Parts of a Chromosome • Sister chromatids: identical copies of a chromosome • Made during the S phase of the cell cycle • Centromere: holds two sister chromatids together

  13. The Cell Cycle

  14. The Cell Cycle • Interphase: • G1 phase: cell growth • S phase: DNA is replicated/copied • G2 phase: more cell growth • Mitotic Phase: • Mitosis/Cell Division • Cytokinesis (division of cytoplasm)

  15. G2 of Interphase Prophase Centrosomes • mitotic • spindle Mitosis Metaphase chromatin -uncondensed chromosomes -sister chromatids/chromosomes -nuclear envelope breaks down -metaphase plate -cleavage furrow -chromosomes pull apart Chromosomes move to middle -nuclear envelope reforms Telophase & Cytokinesis Anaphase (Figure 12.6 in your book)

  16. Mitosis Prophase Anaphase Metaphase Telophase

  17. Prophase of Mitosis • Chromatin coils up into visible chromosomes • Centrioles migrate to opposite ends • Nuclear envelope and nucleolus break down • Centromere of chromosome starts to attach to spindle fibers

  18. Metaphase of Mitosis • Chromosomes line up in the middle of the cell

  19. Anaphase of Mitosis • Spindle fibers contract (shorten) • Chromosomes are pulled apart • Sister chromatids move to opposite poles

  20. Telophase of Mitosis • Chromosomes gather at opposite poles • Nuclear envelope starts to reform

  21. Cytokinesis • Division of the cytoplasm • Plant Cells: cell plate is formed  cell wall • Animal Cells: cleavage furrow formed

  22. Summary of Mitosis • Start with 1 parent cell and ends with 2 daughter cells • 2 daughter cells are formed that are genetically identical to the parent cell • Occurs in somatic cells (aka, body cells) • Functions in growth and repair of cells

  23. Virtual Animation of Mitosis • Check out this site: Virtual Mitosis Animation

  24. Cell Cycle Regulation • Cyclin – a group of proteins that regulates the timing of the cell cycle • Controls when cells go from G1 to S phase • Controls when cells go from S to G2 phase • Controls when cells go from G2 to M phase

  25. Uncontrolled Cell Growth • Cancer – abnormally rapid cell division • Cells of the tumor may break lose and spread or metastasize through the body • May be caused by radiation, pollution, bad luck, viral exposure • Many cancer cells have a mutation/defect in gene p53 (gene that normally tells the cell to wait until all chromosomes have been replicated before proceeding to mitosis)

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