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"Biology is the only science in which multiplication means the same thing as division."

MEIOSIS . "Biology is the only science in which multiplication means the same thing as division.". Meiosis. Comes from a Greek word that means: “ to make smaller ”. Learning Goals: (for this section). 1. Explain the difference between Mitosis and Meiosis.

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"Biology is the only science in which multiplication means the same thing as division."

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  1. MEIOSIS "Biology is the only science in which multiplication means the same thing as division."

  2. Meiosis • Comes from a Greek word that means: • “to make smaller”

  3. Learning Goals:(for this section) • 1. Explain the difference between Mitosis and Meiosis

  4. 2. Descibe how chromosomes determine sex.

  5. 3.Explain why sex-linked disorders occur in one sex more than in the other.

  6. Interpret a pedigree

  7. Section vocab:

  8. MCAS: Unit: HeredityE.U: Organisms reproduce either asexually or sexually. Sexual reproduction leads to a genetic variation.

  9. Why does a pug….

  10. Look so different from a… Doberman pincher?

  11. Answer? Meiosis

  12. Two Kinds of Reproduction • Asexual • One parent cell is needed to reproduce ex. Mitosis • Sexual • Two parent cells join together to form a new individual. • Requires meiosis !

  13. Review of mitosis:

  14. There are two categories of cells in the human body: • 1.) Somatic cells (body cells) • Have 46 chromosomes in every nucleus of every cell. • These cells are produced through mitosis

  15. 2.) Sex cells: • Eggs in females • Sperm in males • All contain only 23 chromosomes (1/2 that of body cells) These cells are produced by meiosis.

  16. WHEN SEX CELLS ARE MADE, CHROMOSOMES ARE COPIED ONCE AND THEN THE NUCLEUS DIVIDESTWICE.

  17. HOW DOES MEIOSIS HAPPEN? • One cell produces 4 cells with ½ the DNA • Meiosis: An Interactive Animation

  18. EACH OF THE NEW CELLS HAS HALF THE NUMBER OF CHROMOSOMES THAT WERE FOUND IN THE ORIGINAL CELL!

  19. WHAT DOES MEIOSIS PROVIDE IN A SPECIES? Variation !

  20. A Comparison of Mitosis and Meiosis both mitosis meiosis

  21. SEX CHROMOSOMES: • Contain genes that determine an offspring’s sex • HUMAN FEMALES HAVE: Xand X • HUMAN MALES HAVE: X and Y

  22. What are the chances of getting a boy or a girl? (use a Punnett Square!)

  23. Karyotype:a picture of human chromosomes all lined up:

  24. Pedigree: • A diagram that shows the occurrence of a trait in several generations of a family.

  25. Sex-Linked Disorders: • Colorblindness • Hemophilia • Cystic Fibrosis • The genes for these disorders are carried on the sex chromosomes- girls have a 2nd X chromosome to mask it. Boys therefore, have the disorder more than girls.

  26. Selective Breeding • Organisms with desired characteristics are mated

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