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Bell Ringer

Bell Ringer. How many cells are created (from 1) at the end of Meiosis? What’s the difference between diploid and haploid? During which stage of Meiosis do homologous chromosomes pair up?. Mitosis vs. Meiosis. Biology February 7, 2014. Mitosis vs. Meiosis. MUST KNOW!.

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Bell Ringer

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  1. Bell Ringer • How many cells are created (from 1) at the end of Meiosis? • What’s the difference between diploid and haploid? • During which stage of Meiosis do homologous chromosomes pair up?

  2. Mitosis vs. Meiosis • Biology • February 7, 2014

  3. Mitosis vs. Meiosis MUST KNOW! • Makes genetically identical cells. • Makes diploid cells. • Takes place throughout lifetime. • Involved in asexual reproduction. • Makes genetically unique cells. • Makes haploid cells. • Takes place at certain times in life cycle. • Involved in sexual reproduction.

  4. What’s the purpose of Meiosis? To create gametes!

  5. Two Types of Cells • Somatic Cells • aka Body Cells • Make up most of the body tissues and organs. • NOT Passed to children • Ex: kidney cells, muscle cells, skin cells, eye cells, etc. • Gametes • aka Sex Cells • aka Germ Cells • Passed to children • Fuse together during fertilization

  6. Gametes • Eggs • Sperm

  7. How do we make Gametes? Meiosis!

  8. Gametogenesis Another name for Meiosis: Gametes Genesis or Creation The Creation of Gametes

  9. Sperm • 1 diploid cell forms 4 haploid sperm.

  10. Sperm

  11. Eggs • 1 diploid cell forms 1 haploid sperm and 3 polar bodies.

  12. Eggs 3

  13. When do egg and sperm come together? (Be appropriate) Fertilization

  14. Fertilization • Sex cells (sperm and egg) nuclei fuse to form ONE nucleus (zygote). • Why don’t fertilized eggs (zygotes) have too many chromosomes?

  15. Let’s Review Meiosis

  16. Meiosis I

  17. Meiosis II

  18. What happens during Prophase I? • Chromosomes condense • Homologs pair up (forms tetrad) • Nuclear envelope breaks down • Spindle fiber forms • CROSSING OVER OCCURS!

  19. nonsister chromatids Tetrad Crossing Over - variation chiasmata: site of crossing over variation

  20. Crossing Over • When homologous chromosomes (from mom and dad) pair up and exchange portions of their chromatids. • Makes each of the four cells at the end of meiosis different from each other. • Creates diversity.

  21. Asexual vs. Sexual Reproduction • Asexual Reproduction • Involves on one parent • Divides by MITOSIS • ALL offspring are identical • Sexual Reproduction • Involves two parents • Each parent contributes a cell made through MEIOSIS • ALL offspring are different

  22. Review • Where do we find genetic material in a cell? • What must happen during Interphase before a cell can enter Prophase I? • 2n means what? • n means what? • Which process (term) describes the process of producing gametes? • When do chromosomes form tetrads? • What happens while chromosomes are in tetrads? • Why is crossing over important?

  23. Review • What type of cell is a stomach cell? • What are two types of germ cells? • How many chromosomes are in a human gamete? • What do we call the fusion of haploid gametes? • During which stage of Meiosis does Crossing Over take place? • If an organism’s diploid number is 24, how many chromosomes will be found in its egg cell? • If an organism’s haploid number is 17, how many chromosomes will be found in a kidney cell? Sperm cell? • Which process replicates chromosomes?

  24. Quizlet • Have your vocab. already assembled for you (starting with the next chapter). • Instant Flash Cards, Games, etc. • Review cards and study guides for state test. • http://quizlet.com/join/63NPw9SjY

  25. Independent Practice Ch. 6-1, 2 Test Monday! • Complete “Comparing Mitosis and Meiosis” worksheet. (If time, we’ll review before bell.) • Study for Ch. 6-1,2 (2 sections) • Make up missing quizzes or tests

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