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Understanding Meiosis: Genetic Recombination & Variation

Explore the intricate process of meiosis, reduction division, and genetic recombination to create specialized reproductive cells. Discover the differences between mitosis and meiosis, stages of meiosis, and the importance of chromosomes in creating genetic diversity.

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Understanding Meiosis: Genetic Recombination & Variation

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  1. What is Meiosis Exactly? • Meiosis is a form of cell division that __________ the number of chromosomes when forming specialized reproductive cells such as gametes or spores • There are ___ stages of meiosis, Meiosis 1 and meiosis 2 • Meiosis 1 and 2 create 4 _________ cells all together

  2. MITOSIS VS. MEIOSIS • Mitosis- process that happens during 1) _________ 2) asexual reproduction 3) __________4)regeneration • AFTER 4 STAGES (P-M-A-T) and 1 cell division IT PRODUCES 2 CELLS ___________ (CLONES) TO THE PARENT CELL- SAME DNA VS. • Meiosis- process that happens to make sex cells (egg and sperm) • AFTER __ STAGES (PMAT-P2M2A2T2) and 2 cell divisions, IT PRODUCES 4 CELLS WITH DIFFERENT GENETIC INFO FROM PARENT

  3. REMEMBER CHROMOSOMES • IN ALL BODY CELLS THEY COME IN PAIRS (2N) CALLED THE ________________. ONE OF THE PAIR IS FROM MOM/DAD. • We have 46 chromosomes in body cells- 23 pairs. • SINCE IN SEX CELLS THERE NEEDS TO BE ½ THE # OF CHROMOSOMES, THEY ARE NO LONGER IN PAIRS…THEY ARE ALONE. THIS IS CALLED THE HAPLOID (HALF) NUMBER (1N) • We have 23 chromosomes in egg/sperm.

  4. IV. Meiosis – Reduction Division

  5. Prophase I:Prophase II: Metaphase I:Metaphase II: Anaphase I:Anaphase II: Telophase I:Telophase II:

  6. Stages of Meiosis 1

  7. Stages of Meiosis 2

  8. S phase of Interphase

  9. Interphase after replication

  10. I. Meiosis (Reduction Division) A. Meiosis I 1. Prophase I a. _____________ become distinct b. nucleolus and nuclear membrane disappear and spindle fibers appear

  11. Prophase I c. spindle fibers appear d.____________–homologous chromosomes . Line up together

  12. Prophase I e. _________________may occur 1) portions of chromatid from one parent break off and attach to a homologous chromatid from the other parent 2) results in ____________________

  13. 2. Metaphase I a. chromosomes line up along the midline b. sister chromatids___________separate

  14. 3. Anaphase I a. at random, one member of each homologous pair moves to the opposite poles (_____________- ____________)

  15. 4. Telophase I and Cytokinesis I a. chromosomes reach opposite poles b. cytokinesis begins

  16. Telophase I c. resulting cells have the n or ____________number of chromosomes 1) one member of each homologous pair with two attached chromatids d. each new cell contains ½ the the number of chromosomes as the original cell

  17. B. Meiosis II 1. Prophase II a. spindle form and chromosomes begin to move toward the mid-line of the cell

  18. . Metaphase II a. chromosomes move to the ______________of the dividing cell

  19. 3.Anaphase II a. ____________ separate and move to the opposite poles of the cell

  20. 4. Telophase II a. nuclear membrane forms around the nucleus in each cell b. each resulting cell contains the _______________of chromosomes

  21. Meiosis 1 and Meiosis 2

  22. D. Genetic Recombination and Variation 1. independent assortment 2. __________ over 3. _____________ fusionof sperm and egg

  23. E. Formation of Gametes 1. spermatogenesis – results in 4 viable sperm 2. oogenesis – results in 1 egg and 3 ________ ____________

  24. Spermatogenesis

  25. Oogenesis

  26. Fertilization [sperm (n) + egg (n)  zytote (2n) ]

  27. Karyotype 1. picture of homologous chromo- somes and sex chromosomes 2. used to detect chromosome abnormalities

  28. Human Chromosomes

  29. Work on the karyotyping project • www.biology.Arizona.edu/

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