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Mitosis Review

Mitosis Review. asexual reproduction Occurs in what cells?. 1. ________________ 2. _______________ 3. _________________. 4. ________________ 5. _______________ . 1. Teolphase 2. Prophase 3. Metaphase. 1. Interphase 2. Anaphase . Meiosis.

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Mitosis Review

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  1. Mitosis Review asexual reproduction Occurs in what cells?

  2. 1. ________________ 2. _______________ 3. _________________ 4. ________________ 5. _______________

  3. 1. Teolphase 2. Prophase 3. Metaphase 1. Interphase 2. Anaphase

  4. Meiosis sexual reproduction Occurs in what cells?

  5. Why Meiosis happens? Meiosis is the division and production of sex cells (gametes)Used in fertilization.

  6. How is Meiosis Different than Mitosis? There are 2 divisions in meiosis Meiosis I and Meiosis II The result is 4 genetically different cells instead of 2 genetically identical In meiosis II, the DNA is not replicated again. (No interphase) The ending number of chromosomes is 23 (egg has 23 and sperm has 23) This is haploid number represented by (n)

  7. Meiosis Summary • Meiosis is sexual reproduction • 4 genetically different daughter cells resulting from 2 divisions. • Forms GAMETES (sex cells)

  8. Meiosis I • The SEX cell undergoes: • Interphase • Prophase I • Metaphase I • Anaphase I • Telophase I • During these phases it is the HOMOLOGOUSchromosomes that become separated.

  9. HOMOLOGOUS chromosomes • Homologous chromosomes are similiar but NOT identical. • One chromosome of each homologous pair comes from the mother and one comes from the father. • Each carries the same genes in the same order, but the alleles for each trait may not be the same.

  10. Interphase • Chromosomes duplicate

  11. Prophase 1 • Homologous chromosomes pair and exchange genetic segments, this is called crossing over. • Crossing OverThe exchange of genetic material between homologous chromosomes this contributes to genetic diversity.

  12. Crossing Over • https://youtu.be/5x_Rp1mwotQ

  13. Chiasmata – sites where crossing over occurs. • Crossing over produces recombinantchromosomes. • What does this mean?

  14. Metaphase 1 Homologous chromosomes align at the equatorial plate. AKA: Metaphase plate Tetrads are formed: tight grouping of two chromosomes, each consisting of two sister chromatids

  15. Anaphase 1: • Homologous pairs separate with sister chromatids remaining together. • Telophase 1: • Two haploid daughter cells are formed. • Each new daughter contains only one chromosome of the homologous pair.

  16. Meiosis II • DNA is not replicated again. • (No interphase) • The result is 4 daughter cells instead of 2 • These resulting daughter cells differ from parent, and each other. • Meiosis reduces the number of chromosomes by half. • The ending number of chromosomes is 23 • (egg= 23 and sperm= 23) • This number is haploid (n)

  17. Meiosis II Second division of meiosis: Gamete formation • Prophase 2: DNA does not replicate; therefore each cell has half the number of chromosomes as the parent cell. (2 haploid cells) • Metaphase 2: Chromosomes align at the equatorial plate. • Anaphase 2: Centromeres divide and sister chromatids migrate separately to each pole. • Telophase 2: Cell division is complete. Four haploid daughter cells are obtained.

  18. Compare mitosis and meiosis…What are some differences?

  19. Mitosis Vs. Meiosis Mitosis 1 division=2 cells Daughter cells identical Diploid Chromosomes (2n)=46 Body cells Meiosis 2 divisions = 4 cells Daughter cells different Haploid Chromosomes (n)=23 Gametes (sex cells)

  20. https://youtu.be/toWK0fIyFlY

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