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Mitosis/Cell Division Review

Mitosis/Cell Division Review. A. B. C. D. E. Meiosis . Produces gametes or sex cells (sperm and egg cells) Occurs ONLY in the reproductive organs. Products of Meiosis = 4 new cells. AND. Divides the chromosome number in half. For Example: . Parent Cell. 4 daughter cells.

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Mitosis/Cell Division Review

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  1. Mitosis/Cell Division Review

  2. A B C D E

  3. Meiosis • Produces gametes or sex cells (sperm and egg cells) • Occurs ONLY in the reproductive organs

  4. Products of Meiosis = 4 new cells AND Divides the chromosome number in half

  5. For Example: Parent Cell 4 daughter cells

  6. 2 Sets of Divisions 1st division is exactly like mitosis except sister chromatids stay together

  7. Before the 1st division takes place DNA MUST replicate

  8. Prophase I • Chromosomes condense • Homologous chromosomes pair together • Crossing over occurs

  9. Crossing Over

  10. Metaphase I • Homologous pairs are moved to the equator (middle) of the cell

  11. Anaphase I • Homologous pairs separate • Chromatids remain together • Genetic material has been recombined

  12. Telophase I • Chromosomes gather at poles • Cytoplasm divides

  13. 2nd DIVISION BEGINS DNA replication DOES NOT occur

  14. Prophase 2 • New spindles form around chromosomes • Crossing over – does not occur!

  15. Metaphase 2 • Chromosomes align along with equator (middle) of the cells

  16. Anaphase 2 • Sister chromatids (now called chromosomes) divide and move to opposite poles

  17. Telophase 2 • Chromosomes gather at the poles • Nuclear envelope forms and cytoplasm divides 4 new daughter cells, each genetically DIFFERENT, are formed and are all haploid

  18. Sexual Reproduction • Haploid cells join to make diploid cells • Increase in genetic variation • Leads to change or evolution

  19. Females: meiosis occurs before birth Each month, one egg is matured and released for possible fertilization Males: meiosis begins at puberty and continues until death

  20. Asexual Reproduction • Single parents pass genes to offspring • Clones • Prokaryotes, yeast, hydra • Faster to produce offspring, but no genetic variation

  21. GENETIC VARIATION • The chromosome a gamete will receive depends on the way it lines up at the equator Independent assortment

  22. The Importance • Lead to the evolution of a species • Increase survival

  23. CANCER • Cells have checkpoints to determine if they are healthy enough to divide • If those checkpoints are faulty, cells can divide and grow uncontrollable – can form a tumor and lead to cancer

  24. What’s the problem with more cells? 1.) Steal nutrients from healthy cells which eventually die

  25. 2.) Can travel from their original location • METASTASIZE

  26. Causes of Cancer • Exposure to chemicals or toxins • Radiation • Viruses • Your Own Genetics

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