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Genes are in Nucleus of Eukaryotic Cells. 1930s. 1. Concluded: Genes are on Chromosomes. Prokaryotes: Circular chromosomes, Binary Fission Eukaryotes: Linear chromosomes, Mitosis and Meiosis. 2. Chromosome Number . Field Horsetail. 3. Drosophila melanogaster Chromosomes.
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Concluded: Genes are on Chromosomes Prokaryotes: Circular chromosomes, Binary Fission Eukaryotes: Linear chromosomes, Mitosis and Meiosis 2
Chromosome Number Field Horsetail 3
Drosophila melanogaster Chromosomes Diploid (2n = 8), 4 distinct chromosomes 3 autosomes, one pair of sex chromosomes (X & Y) female male polytene chromosomes 4
Rice Chromosomes Oryza sativa 2n = 24; 12 pairs of chromosomes 5
Human Chromosomes 22 pairs of autosomes, one pair of sex chromosomes (X & Y) 6
Descriptions of Eukaryotic Chromosomes Unreplicated (G1) and Replicated (G2) one chromatid two sister chromatids per chromosome per chromosome 7
Descriptions of Eukaryotic Chromosomes All unreplicated chromosomes pictured 8
Eukaryotic Cell Cycle Eukaryotes: Linear Chromosomes, Mitosis and Meiosis Replicated Unreplicated 10
Mitosis - growth and healing Interphase Prophase - Chromosomes condense Metaphase Chromosomes align independently Anaphase Sister chromatids segregate Telophase Cytokinesis 11
Mitosis - Prophase A A BB a a b b 12
Mitosis - Metaphase & Anaphase a a BB A A b b a a B B A A b b 13
Mitosis - Telophase a a B B A A b b 14
Highlights of Mitosis A A a a BB b b a A B b Diploid cell Replicated chromosomes Diploid cells Unreplicated chromosomes 15
Cytokinesis Cell furrow Cell plate 16
Meiosis - Formation of Haploid Gametes A A a a BB b b a A b B a A b B Diploid cell (one) Replicated chromosomes Haploid cells (four) Unreplicated chromosomes 17
Highlights of Meiosis A a a A b b B B Chromosomes replicate once, cell divides twice Homologous chromosomes pair then segregate Chromosome number is reduced - diploid to haploid Each gamete receives one of each type of chromosome with one copy of each type of gene OR 18
Stages of Meiosis I - Prophase Leptonema - chromosomes condense Zygonema - homologous chromosomes pair Pachynema - Tetrads easily seen, crossing over occurs Diplonema - Chiasma easily seen Diakinesis - Terminalization, chiasmata resolved 19
Stages of Meiosis I - Prophase Leptonema - chromosomes condense Zygonema - homologous chromosomes pair 20
Stages of Meiosis I - Prophase Pachynema - tetrads easily seen, crossing over occurs Diplonema - chiasma easily seen Diakinesis - terminalization, chiasmata resolved 21
Meiosis I Diploid to Haploid Reductional Division 22
Meiosis II Haploid cell with replicated chromosomes to Haploid cells with unreplicated chromosomes 23
Meiosis I & II Figure 12.9 24
Compare and Contrast: Mitosis & Meiosis Griffith et al. Introduction to Genetic Analysis. 25
Mitosis vs. Meiosis Figure 12.11 26
Spermatogenesis vs. Oogenesis In testis continuous production In ovaries In 3 months fetus, all in Meiosis I prophase Figure 12.13 27
Gametogenesis in Plants Figure 12.15. 28