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Section 6-2 “Meiosis ”

Section 6-2 “Meiosis ”. Write everything that is underlined. KEY CONCEPT During meiosis, diploid cells undergo two cell divisions that result in haploid cells. A. Cells go through two rounds of division in meiosis. Meiosis reduces chromosome number and creates genetic diversity.

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Section 6-2 “Meiosis ”

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  1. Section 6-2“Meiosis” Write everything that isunderlined

  2. KEY CONCEPT During meiosis, diploid cells undergo two cell divisions that result in haploid cells

  3. A. Cells go through two rounds of division in meiosis • Meiosis reduces chromosome number and creates genetic diversity

  4. Meiosis I and meiosis II each have four phases, similar to those in mitosis • Pairs of homologous chromosomes separate in meiosis I • Homologous chromosomes are similar but not identical • Sister chromatids divide in meiosis II • Sister chromatids are copies of the same chromosome homologous chromosomes sister chromatids sister chromatids

  5. Meiosis I occurs after DNA has been replicated • Meiosis I divides homologous chromosomes in four phases

  6. Meiosis II divides sister chromatids in four phases • DNA is not replicated between meiosis I andmeiosis II

  7. Listen Up! • http://www.youtube.com/watch?v=nM-L6q8u_58&safety_mode=true&persist_safety_mode=1 • Follow along on a sheet Miss Walsh will pass out. • Goofy? Yes. Helpful? Absolutely!!!!!

  8. Hands On! • Each table will receive 5 pieces of yarn- one big piece, tied into a circle, and 4 little pieces, which represent homologous chromosomes. • Miss Walsh will call out a step of meiosis I- using your textbook (page 174) and pieces of yarn, demonstrate each step. • Miss Walsh will call out the phases of meiosis II- use your textbook (page 175) and yarn to demonstrate each step. (…You are going to need scissors for Meiosis II)

  9. Meiosis differs from mitosis in significant ways • Meiosis has two cell divisions; mitosis has one • In mitosis, homologous chromosomes never pair up • Meiosis results in haploid cells; mitosis results in diploid cells

  10. B. Haploid cells develop into mature gametes • Gametogenesis is the production of gametes • Gametogenesis differs between females and males • Sperm become streamlined and motile • Sperm primarily contribute DNA to an embryo • Eggs contribute DNA, cytoplasm, and organelles to an embryo • During meiosis, the egg gets most of the contents; the other cells form polar bodies

  11. The Fate of the 4 Haploid Cells… • If it is from the male parent, all 4 will become sperm cells • If it is from the female parent, 1 will be an egg and the other 3 gametes die

  12. Pick 1 of the 3 below: • -Draw and label the following picture • Write a paragraph about what is happening in the pictures • Write a rap about what is occurring in the pictures

  13. DNA copies itself Diploid Parent Cell 1st meiotic division (haploid) 2nd meiotic division (haploid)

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