BIOL 101 1nd Edition Lecture 12 Outline of Last Lecture I Reproduction II Eukaryotic Cell Cycle III Anatomy of Chromosomes IV Cancer Outline of Current Lecture I Diploid vs Haploid II Meiosis III Cycle 2 of Meiosis IV Differences Current Lecture Meiosis Class discussion I Multicellular organisms like animals plants and ourselves inherit one set of chromosomes from each parent when a sperm fertilizes an egg These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Meiosis fertilization zygote mitosis II Meiosis is a type of cell division that produces haploid gametes in diploid organisms i Diploid organisms contain a set of homologous chromosomes in their somatic cells ii The diploid number or 2n in humans 46 iii Diploid organisms produce haploid gametes 1 Examples sperm egg iv The haploid number or n in humans 23 III Meiosis reduces the chromosome number from diploid to haploid i Diploid or Haploid diploid cell ii What would the haploid gametes of this cell look like One cell would have the black chromosomes one cell would have the white chromosomes iii What is n 3 IV In meiosis I HOMOLOGOUS CHROMOSOMES don t always have the same allele separate Illustrate meiosis I below V In meiosis II SISTER CHROMATIDS duplicated chromosome same allele separate Illustrate meiosis II below Crossing over occurs in prophase one The DNA does not get replicated the second time Key differences between meiosis and mitosis Tetrads form during meiosis VI Chromosomes orient independently at the metaphase plate i What does this mean and how do the equally probable arrangements of chromosomes contribute to genetic diversity You never know which chromosomes going to be on which side
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