BIOL 120 1st Edition Lecture 16 Outline of Last Lecture I Other types of photosynthesis II Meiosis Overview Outline of Current Lecture I Overview of Meiosis II Mitosis vs Meiosis III Crossing Over IV Results of Meiosis V Mendel s Experiment Current Lecture I Overview of Meiosis A Meiosis reduces chromosome number by half diploid to haploid B Consist of two cell divisions Meiosis I and Meiosis II 1 Meiosis I diploid parent cell produces two daughter cells a homologs in each chromosomes pair separate and go to different daughter cell b haploid daughter cells still have chromosome of two identical sister chromatid 2 No replication after Meiosis I 3 Meiosis II sister chromatid of each chromosome separate and go to different daughter cells a similar to mitosis 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 b produces 4 haploid daughter cells called gametes through the process of gametogenesis C Fertilization of gametes 1 results in a zygote a fertilized cell containing a full complement of chromosomes diploid 2 receives a haploid chromosome set from both mother and father D Meiosis Division 1 Interphase DNA replication 2 Meiosis I separation of homologous chromosomes a Prophase I b Metaphase I c Anaphase I d Telophase I 3 Meiosis II a Prophase II b Metaphase II c Anaphase II d Telophase II 4 Cytokinesis II Mitosis vs Meiosis A Mitosis creates identical diploid daughter cells B Meiosis creates non identical haploid daughter cells III Crossing Over A at the point where chromosomes cross over the non sister chromatid from each homolog physically break at the same point and attach to each other maternal and paternal chromosomes are swapped B Occurs in Prophase I C results in recombinant chromosomes IV Results of Meiosis A four gametes with a chromosome composition different from parent cells B Sexual reproduction creates great genetic variety C Separation and distribution of homologous chromosomes during meiosis I creates variety giving each daughter cell a great deal of genetic diversity 1 humans can produce 8 4 million different combinations of chromosomes in gametes V Mendel s Experiment A Gregor Mendel 19th century monk interested in heredity transmission of traits from parents to offspring 1 understood that all traits have 2 possible alleles 1 from mom and 1 from dad a matching alleles homozygous b different alleles heterozygous 2 Genetics branch of biology that focuses on the inheritance of traits B used peas model organisms for his experiment 1 preventing the plants from self fertilization and pollinated them by hand to control cross pollination 2 Study seed shape seed color pod shape pod color flower color flower and pod position and stem length a phenotype observable features b purelines identical offspring from self pollinated c hybrids created by mating two different pure lines that differed in one or more traits
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