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Why Meiosis?

Use the next two slides to fill in the rectangle at the top of the notes page. It says “meiosis in a nutshell” and “why meiosis?”. Meiosis – in a nut shell Write this: CELL DIVISION RESULTING IN 4 GENETICALLY DIFFERENT DAUGHTER CELLS, CALLED GAMETES , EACH WITH 23 CHROMOSOMES . Why Meiosis?.

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Why Meiosis?

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  1. Use the next two slides to fill in the rectangle at the top of the notes page. It says “meiosis in a nutshell” and “why meiosis?”

  2. Meiosis – in a nut shellWrite this: CELL DIVISION RESULTING IN 4 GENETICALLY DIFFERENT DAUGHTER CELLS, CALLED GAMETES, EACH WITH 23 CHROMOSOMES

  3. Why Meiosis? • Meiosis • To produce gametes (sex) cells which are: • Egg and Sperm cells

  4. Use the next two slides to fill in the 7 terms that are listed in the data table. • I have already given you the definition on the notes page, you need to write the correct terms in the blank on your notes. • Terms are in blue font on the slide.

  5. Terms Review… • Haploid: (n) having a single set of chromosomes in the cell. ex. Gametes; humans have 23 chromosomes in sex cells (egg and sperm cells) • Diploid: (2n) having two sets of homologous chromosome in the cell. ex. Somatic (body) cells; humans have 23 pairs or 46 chromosomes in body cells Human Karyotype with 23 pairs of homologous chromosomes for a diploid number of 46; 2n = 2(23) = 46

  6. Terms Continued • Homologous chromosomes – two sets of chromosome in a pair, with one set coming from a male parent and the other set coming from the female parent. • Tetrad – pairing of homologous chromosomes during meiosis I, • and such pairing has 4 (tetra) chromatids. These chromatids • can then exchange genetic material. • Crossing-over – process in which tetrad of homologous • chromosomes exchange portions of their chromatids, and thus • genetic material is exchanged; this occurs during Prophase I of meiosis. • Gametes – sex cells; involved in sexual reproduction. Male gametes are called sperm cells and female gametes are called egg cells; sperm are produced in testes and egg are produced in ovaries by meiosis.

  7. The next slide should be used to fill in the box that says “crossing over”

  8. Crossing Over • What is happening?Exchange of genetic material between homologous chromosomes • How does this affect the individual (offspring)? Creates genetic variation

  9. The next four slides should be used to fill in the box with the “a, b, c, d” listed sentences. • You have to READ the sentences on “a, b, c, d” in order to fill in the correct answers from the questions on the next 4 slides. Pay attention.

  10. Meiosis Review • Is the beginning parent cell diploid or haploid (2n or n)? 2. Are the resulting daughter cells diploid or haploid (2n or n)? Diploid haploid

  11. More Meiosis Review 3. How many daughter cells are produced? 4 different Are the resulting daughter cells different from the parent cell?

  12. More Meiosis Review 5. Are the resulting daughter cells different from each other? different 46 23 6. How many chromosomes are in a human parent cell? 7. How many chromosomes are in a human daughter cell?

  13. More Meiosis Review 8. What types of cells are produced by meiosis? Gametes, which are eggs and sperm

  14. The next two slides will help you complete the data tables at the bottom of the notes page. • Fill in the data table with a check or “x”

  15. Mitosis vs. Meiosis √ √ √ √ √ √

  16. √ √ Mitosis vs. Meiosis √ √ √ √

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