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Cell Division

Cell Division. By: Amber Tharpe. Activation. Humans make 2 trillion new cells per day. Cell Cycle. 2 main parts Interphase- Cell is normal Mitosis- Cell is dividing Cytokinesis- occurs at the end of mitosis. Interphase. When cell is not dividing Cell spends 90% of its life here

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Cell Division

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  1. Cell Division By: Amber Tharpe

  2. Activation • Humans make 2 trillion new cells per day

  3. Cell Cycle • 2 main parts • Interphase- Cell is normal • Mitosis- Cell is dividing • Cytokinesis- occurs at the end of mitosis

  4. Interphase • When cell is not dividing • Cell spends 90% of its life here • DNA is called chromatin and is not condensed • DNA and organelles double to prepare for cell division

  5. Interphase has 3 parts: • Gap1(G1)- cell carries out normal functions and doubles organelles at the end • Synthesis (S)- DNA is doubled • Gap 2 (G2)- additional cell growth

  6. Different types of cells divide at different rates • G0- stage where cell performs normal functions but does not divide • Cell must have an adequate surface area to volume ratio to contain all the necessary organelles and molecules but still get nutrients in and wastes out

  7. Cancer • Uncontrolled cell growth • Continuous mitosis without interphase

  8. Benign- harmless cancer cells that remain clumped together • Malignant- harmful cancer cells break away • Metastasize- when cancer cells break away and form tumors elsewhere • Carcinogens- substances that promote the development of cancer • Ex: UV light and air pollutants

  9. Chromosome Structure • Chromosome- long thread of DNA with numerous genes; Condensed and looks like an X • Histones- proteins that DNA wraps around • Chromatin- loose DNA that is not condensed • Chromatid- half of a duplicated chromosome • Centromere- region where sister chromatids are held together • Telomeres- ends of DNA with repeating nucleotides without genes; short section is lost each time DNA is copied

  10. Mitosis • Divides DNA into 2 nuclei • Makes 2 daughter cells with a diploid number • Used for growth and repair • Also used in some asexual reproduction

  11. 4 stages (P-M-A-T) Prophase Metaphase Anaphase Telophase

  12. Stages of Mitosis (P-M-A-T) Prophase Early Prophase Interphase http://micro.magnet.fsu.edu/micro/gallery/mitosis/mitosis.html Metaphase Early Anaphase Telophase Anaphase

  13. Prophase DNA condenses Nuclear envelope dissolves Spindle fibers start to form

  14. Prophase(in animal cell and onion cell)

  15. Metaphase Chromosomes align in the equator (middle) of the cell Spindle fibers attach to the chromosomes to move them

  16. Metaphase

  17. Anaphase Sister chromatids separate to opposite poles Spindle fibers split chromosomes at the centromere, forming sister chromatids

  18. Anaphase

  19. Telophase • 2 nuclear envelopes form around the separated DNA • Spindle fibers dissolve • In animal cells • Cell membrane pinches in (cleavage furrow) • In plant cells • Cell plate forms which later becomes 2 cell walls

  20. Telophase

  21. Cytokinesis Cytoplasm and organelles divide 2 cells form

  22. http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=2&rg=animated_biology&at=animated_biology&var=animated_biologyhttp://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=2&rg=animated_biology&at=animated_biology&var=animated_biology

  23. Animation of Stages of Mitosis http://biology.about.com/library/blmitosisanim.htm

  24. Asexual Reproduction 1 parent Offspring is identical to parent Less genetic diversity

  25. Binary Fission Asexual reproduction for bacteria DNA is copied in 1 cell The cell divides into 2 cells with the same DNA

  26. Binary Fission

  27. Other Types of Asexual Reproduction • Budding - a small projection form on the parent with forms a new organism • ex: hydra and yeast • Fragmentation - when a parent splits into pieces, each piece is a new organism • ex: flatworms and sea stars • Vegetative reproduction- when new plants form from runners • Ex: some grasses

  28. http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=2&rg=animated_biology&at=animated_biology&var=animated_biologyhttp://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=2&rg=animated_biology&at=animated_biology&var=animated_biology

  29. Chromosome Long thread of DNA containing many genes X- shaped

  30. Somatic cells Body cells All cells not involved in reproduction Diploid cells (2N) Contains 2 copies of each chromosome In humans 46 chromosomes Made by mitosis

  31. Gametes Sex cells Egg (female) or sperm (male) Haploid cells (1N) Contains 1 copy of each chromosome In humans 23 chromosomes Made by meiosis Used in sexual reproduction

  32. Autosomes • Chromosome pairs 1-22

  33. Sex Chromosomes Chromosome pair 23 for gender Either X or Y XX is female XY is male

  34. Sexual Reproduction Offspring are a mixture of both parents Occurs by meiosis then fertilization Meiosis Formation of gametes Makes haploid cells from diploid cells Fertilization The actual fusion of the 2 gametes First cell is called a zygote

  35. Meiosis Process of making gametes for sexual reproduction Events that occur during meiosis allows for greater genetic diversity

  36. Meiosis Meiosis I Makes 2 unique diploid cells Prophase I – Telophase I Interphase without duplicating DNA Meiosis II Makes 4 unique haploid cells Prophase II – Telophase II

  37. Prophase I • Similar to prophase in mitosis • crossing over occurs • homologous chromosomes line up and sections of the chromosomes overlap and become incorporated into the other • Allows for genetic diversity

  38. Metaphase I • Homologous chromosomes pair up at the equator- 2 lines of chromosomes in the middle • Independent Assortment • Allows for genetic diversity • When homologous chromosomes line up in the middle, some chromosomes from the mother and father line up on either side

  39. Anaphase I • Homologous chromosomes separate to opposite poles • Sister chromatids remain together (looks like W’s)

  40. Telophase I • Similar to telophase in mitosis • Makes 2 cell with unique combinations of chromosomes • At the end of Meiosis I, 2 diploid cells that are genetically unique are formed • What Makes Meiosis I Different from Meiosis II? • Between telophaseI and prophase II- DNA is not replicated

  41. Prophase II • Similar to prophase in mitosis • DNA was not doubled • Only one copy of each chromosome • Starting with half the DNA of prophase I

  42. Metaphase II • Chromosomes line up in the middle- single file line • Half the chromosomes of Metaphase I

  43. Anaphase II • Sister chromatids are pulled to opposite poles • Half the chromatids of Anaphase I

  44. Telophase II Produces 4 haploid cells with unique combinations of chromosomes Females produce 1 ovum (egg) and 3 polar bodies Males produce 4 sperm cells

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