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THE CELL CYCLE and CELL DIVISION

THE CELL CYCLE and CELL DIVISION. Think about it… why do cells stay small?. DNA Overload = Limit to Cell Growth. The information stored in that DNA is able to meet all of the cell’s needs in a small cell If a cell grows too large, the DNA cannot produce enough proteins to supply the cell.

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THE CELL CYCLE and CELL DIVISION

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  1. THE CELL CYCLE and CELL DIVISION

  2. Think about it…why do cells stay small? DNA Overload = Limit to Cell Growth The information stored in that DNA is able to meet all of the cell’s needs in a small cell If a cell grows too large, the DNA cannot produce enough proteins to supply the cell

  3. CELL DIVISION -before it becomes too large, a growing ‘parent’ cell divides into 2 ‘daughter’ cells **Before cell division occurs, the cell replicates all of its DNA, one set/daughter **2 main stages of eukaryotic cell division: • Mitosis – division of the cell nucleus • Cytokinesis– division of cell cytoplasm

  4. Liver cell completes cell division – Magnification 11,500x

  5. Chromosomes • Genetic information is passed from one generation to the next on chromosomes(made of DNA). • Chromosomes are only visible in most cells during cell division (other times, the DNA is in the not visible chromatinstate) • Before cell division, the DNA condenses into compact structures, chromosomes

  6. Chromosomes • Once copied, each chromosome consists of two identical “sister” chromatids. • Centromere –attachment • After cell division, each new cell receives one sister chromatid Sister chromatids Centromere

  7. THE CELL CYCLE

  8. The Cell Cycle • During the cell cycle: • a cell grows • prepares for division • divides • Interphase is the period of growth that occurs between cell divisions • -followed by mitosis and cytokinesis

  9. The Cell Cycle

  10. Animated Cycle http://www.cellsalive.com/cell_cycle.htm

  11. increases in size • synthesizes proteins & organelles • chromosome replicated • DNA synthesis takes place • Enters S phase • completes cycle • organelles and molecules required for cell division are produced • Once G2 is complete, the cell is ready to start the M phase—Mitosis

  12. Mitosis The process of cell division which results in the production of two daughter cells from a single parent cell The daughter cells are identical to one another and to the original parent cell.

  13. Mitosis • Prophase • Metaphase • Anaphase • Telophase

  14. Mitosis: PROPHASE Prophase Spindle forming Chromosomes (paired chromatids) Centromere

  15. Spindle forming Prophase • 1st & longest phase • Centrioles separate and take up positions @ nuclear poles • Spindle,a microtubule structure, forms between the centrioles • Nuclear envelope breaks down. Centromere Chromosomes (paired chromatids)

  16. Mitosis: METAPHASE Centriole Spindle Centriole Metaphase

  17. Centriole Metaphase • The chromosomes line up across the center of the cell aka metaphase plate • Microtubules connect the centromeres to the fibers of the spindle. Spindle

  18. Mitosis: ANAPHASE Individual chromosomes Anaphase

  19. Individual chromosomes • Anaphase • Sister chromatids separate into individual chromosomes. • The chromosomes move and separate into two groups.

  20. Mitosis: TELOPHASE Nuclear envelope reforming Telophase

  21. Telophase • Chromosomes gather at opposite ends of the cell & lose their distinct shape • New nuclear envelopes forms around each cluster • Spindle breaks apart & nucleoli reappear

  22. CYTOKINESIS Cytokinesis

  23. Cytokinesis • Not a phase of mitosis • Cell membrane pinches in and the cytoplasm is split between the 2 cells • Each daughter cell has an identical set of duplicate chromosomes

  24. Cytokinesis in Plants • Cell plate forms midway between the divided nuclei. Cell plate Cell wall

  25. Animal Mitosis

  26. Plant Mitosis

  27. Cells in Mitosis http://www.uoguelph.ca/zoology/devobio/210labs/mitosis1.html http://web.mac.com/mrgaskell/iWeb/Science%20Extras/Mitosis%20Slides.html Things to look: Shape of Cell & If there is a division forming between cells Chromosomes & Location Presence of a nucleus

  28. Mitosis Animations • http://www.johnkyrk.com/mitosis.html • http://www.youtube.com/watch?v=VlN7K1-9QB0 • http://outreach.mcb.harvard.edu/animations/biochem.swf • http://www.hybridmedicalanimation.com/anim_mitosis.html • http://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html

  29. Controls on Cell Division • Normal cells reproduce until they come into contact with other cells. • When cells come into contact with other cells, they respond by not growing. • This shows that cell growth and division can be turned on and off.

  30. Cell Cycle Regulators • Regulated by a specific protein called cyclin • Cyclin concentration rises and falls in time with the cell cycle • Internal Regulators: • -Proteins responding to events inside cell • - Allow the cell cycle to proceed only when certain processes have happened inside the cell. • External Regulators: • -Proteins responding to events outside cell • -direct cells to speed up/slow down the cell cycle

  31. Cancer: Uncontrolled Cell Growth • cells lose the ability to control growth. • Cancer cells do not respond to the signals that regulate the growth of most cells. • Cancer cells divide uncontrollably and form masses of cells called tumorsthat can damage the surrounding tissues. • Metastasis-cancer cells may break loose from tumors and spread throughout the body

  32. Cancer Cells • http://science.education.nih.gov/supplements/nih1/cancer/activities/activity2_animations.htm

  33. Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

  34. Prophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

  35. Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

  36. Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

  37. Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

  38. Meiosis • cell division by which germ cells (eggs and sperm) are produced. • One parent cell produces four daughter cells (not genetically identical)

  39. During meiosis, DNA replicates once, but the nucleus divides twice. Daughter cells have half the number of chromosomes (n=haploid) found in the original parent cell(2n=diploid)

  40. Meiosis I • Prophase 1: Each chromosome duplicates and remains closely associated. These are called sister chromatids. • Metaphase 1: Chromosomes align at the center of the cell. • Anaphase 1: Chromosome pairs separate with sister chromatids remaining together. • Telophase 1: Two daughter cells are formed with each daughter containing only one chromosome of the chromosome pair.

  41. Prophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  42. Prophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  43. Metaphase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  44. Telophase I http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  45. MEIOSIS II • Prophase 2: DNA does not replicate. • Metaphase 2: Chromosomes line up at the center of the cell • Anaphase 2: Centromeres divide and sister chromatids move separately to each pole • Telophase 2: Cell division is complete 4 haploid daughter cells are formed

  46. Prophase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  47. Metaphase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  48. Telophase II http://everyschool.org/u/logan/cellreproductionx/rogersa/research/meiosis.html

  49. Meiosis http://www.biosci.uga.edu/almanac/bio_103/notes/apr_3.html.

  50. Meiosis Animation http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/movie/meiosis.htm

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