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AS Academic Tutorial 5. Stem Cell Division

AS Academic Tutorial 5. Stem Cell Division. So what are chromosomes?. http://advancedsciences.cambridge.org/ocr/biology_1/animation/878. Let’s revise the cell cycle. Cytokinesis:. cytoplasm divides. Nucleus divides. growth. new protein and organelles made. mitosis. G1.

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AS Academic Tutorial 5. Stem Cell Division

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  1. AS Academic Tutorial 5.Stem Cell Division

  2. So what are chromosomes? • http://advancedsciences.cambridge.org/ocr/biology_1/animation/878

  3. Let’s revise the cell cycle Cytokinesis: cytoplasm divides Nucleus divides growth new protein and organelles made mitosis G1 Proteins needed for cell division made G2 S DNA replicates

  4. Stem Cell Cyclehttp://www.cellsalive.com/cell_cycle.htm

  5. True or False? • The longest stage in the lifecycle of a stem cell is mitosis. • Mitosis is the division of a nucleus. • Replication of the DNA to produce identical sister chromatids occurs in the G2 phase. • The products of the cell cycle are genetically identical cells. • If there are 10 units of DNA in the original cell in G1, there are 20 in each of the new cells after cytokinesis.

  6. So, before mitosis occurs……. Cell at interphase • Protein synthesis • Organelle synthesis • DNA replication

  7. A single chromosome at the beginning of mitosis Has two chromatids, as the DNA replicates during interphasebefore mitosis centromere

  8. Interphase – normal looking cells

  9. 3 happenings occur in prophase. Early prophase centrioles nucleolus DNA coils and condenses Chromosomes take up stain

  10. prophase Centrioles move apart Nuclear membrane breaks down Nucleolus fades Chromosomes continue to condense

  11. Nucleolus disappears Chromosomes continue to condense What were the 3 happenings?

  12. Prophase – wriggly worms!

  13. metaphase Chromosomes aligned on the equator Nuclear membrane broken down Each chromosome attached to spindle fibre by the centromere

  14. Metaphase – spider’s legs exploding out of middle!

  15. Anaphase Centromeres divide and chromatids pulled apart

  16. Anaphase

  17. anaphase

  18. Anaphase Sister chromatids are pulled to opposite poles of the cell

  19. Anaphase – fingers pulling apart

  20. Telophase – two blobs in one cell

  21. Cytokinesis

  22. Mitosis Animations! • http://uk.youtube.com/watch?v=nPG6480RQo0&feature=related • Musical introduction! • http://uk.youtube.com/watch?v=ELVwj5JDfg8&feature=related • http://www.youtube.com/watch?feature=iv&src_vid=nPG6480RQo0&v=VGV3fv-uZYI&annotation_id=annotation_706798 3D good • http://www.youtube.com/watch?v=cvlpmmvB_m4&feature=endscreen&NR=1 Very clear - good • http://www.cellsalive.com/mitosis.htm

  23. In a moment you will be preparing a root tip squash to look for stained cells like these. Let’s recognise the phases! Interphase

  24. early prophase

  25. prophase

  26. metaphase

  27. Anaphase

  28. Early telophase

  29. Telophase

  30. Cytokinesis in a plant cell

  31. So now to the practical – see instructions in booklet page 4……Draw any 2 cells you find showing different mitotic phases, or 2 cells from the prepared slides. • Biological Drawings • Use the whole page. • Sharp pencil • No shading • No sketching • Labels with arrow heads.

  32. When you have finished…….. • Tidy all your equipment carefully away. • Start answering the quizzes in the booklet pages 1 – 3 and 5, and then go on to the exam questions pages 8 - 13. They start easy and become challenging! • Page 8 should read “ Fig 5.1 shows drawings of nuclei, A to D, from 2 different plant species. Two of them show prophase of mitosis.”

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