Lecture 1 Plant breeding genetic modification The Green Revolution the application of basic genetic principles life in many parts of the developing world was transformed many deaths avoided Eugenics the self direction of human evolution Controlling breeding Eugenical Sterilization Act Nazi Euthanasia based on genetic principles Transmission Genetics from understanding mitosis and meiosis o Mitosis faithful duplication and transmission of genomes during cell division Consider cell numbers human tens of trillions million million Consider genome sizes human n 3 billion bp Consider consequences of errors Cell death Disease o Eukaryotes Haploid diploid Homologous chromosomes Chromosome structure Know centromere telomere kinetochore microtubules chromatids sister chromatids chromosomes Cell cycle G1 S G2 all 3 interphase M mitosis Prophase chromosome condensation spindle formation Prometaphase nuclear membrane melts condensed chromosomes Metaphase chromosomes aligned spindles attaches to begin to align at midline kinetochores Anaphase sister chromatids separates and move to poles Telophase nuclear membrane reforms chromosomes decondense Errors in mitosis and human diseases and disorders o Non disjunction failure of sister chromatids to separate during anaphase somies trisomies nulosomies o Unregulated Cell Division cancer Mitosis Meiosis Review Eukaryotic specie have a characteristic number of chromosomes per cell o Humans 46 chromosomes o No relationship between complexity of organism and number of chromosomes per cell o Two sets of chromosomes one inherited from male one from female parent homologous pair Humans 23 homologous pairs o Most cells carry two sets of genetic information diploid o Reproductive cells contain a single set of chromosomes haploid One copy of each gene Parts of a chromosome o Centromere attachment point for spindle microtubules o Telomere tip of a linear piece of chromosome o Origin of Replication sites where DNA synthesis begins Cell Cycle and MITOSIS o 2 phases Interphase and M phase o Interphase between cell divisions cell grows develops and functions o M phase period of active cell division o Interphase checkpoints and subphases G1 the cell grows G1 S checkpoint holds cell in G1 until it has all enzyme necessary for DNA replication Before this cells can exit from active cycle and pass into nondividing phase called G0 which is a stable state during which cells usually maintain a constant size can reenter active or stay in G0 If pass checkpoint they are committed to divide S phase DNA synthesis each chromosome duplicates G2 G2 M checkpoint passed only is the cells DNA is undamaged Throughout interphase chromosomes are relaxed by not uncoiled o M phase Copies of the cells chromosomes sister chromatids separate and the cell undergoes division 6 stages 5 stages of mitosis and cytokinesis Prophase Chromosomes condense Duplication occurred during S phase but now can visibly see the two chromatids attached at the centromere Spindles form Prometaphase Disintegration of the nuclear membrane Microtubules make contact with the chromosomes at kinetochore Chromosomes align in the center of the cell Spindles come from each end of the cell and attach to chromatids Connection between sister chromatids separate Chromosomes move toward opposite spindle poles Metaphase Anaphase Telophase Chromatids have separated and each is considered a separate chromosome arrived at spindle poles Nuclear membrane re forms around each set of chromosomes Cytokinesis Division of the cytoplasm Sexual Reproduction o 2 processes Meiosis leads to gametes and chromosomes number is half and Fertilization two haploid gametes fuse and restore chromosome number to original diploid value MEIOSIS o 2 divisions after each meiosis I and II o Meiosis I Interphase Prophase I Homologous chromosomes synapse close pairing and condense Crossing over takes place homologous chromosomes exchange genetic information Metaphase I line up Anaphase I two chromatids separate Telophase Chromosomes arrive at spindle poled o Meiosis II breaks down Prophase II chromosomes condense spindles re forms membrane Metaphase II individual chromosomes line up on the metaphase plate with sister chromatids facing opposite poles Anaphase II sister chromatids are pulled to opposite poles Telophase II Haploid number Lecture 2 pathogens and parasites Genetic Variation is the key to survival must constantly evolve because being chased by o Red Queen Hypothesis keep running to stay in place Meiosis is the key to sex halves the size of genome and places it in a gamete so it can be recombined with another gamete to restore the normal genome size Transmission Genetics Karyotype a set of chromosomes as seen during cell division number size shape staining patterns o Our karyotype is 22 pairs of chromosomes plus X and or Y Sex Genetic Variation o Two parents many different combination of progeny humans o 223x223 71 000 000 000 000 combinations o Sex requires halving chromosome number of parents so sexual reproduction results in constant chromosome number meiosis Each product of meiosis receives 1 copy of all chromosomes Cell Cycle o DNA replication during S o 2 Phases of Meiosis Phase I Meiosis I reducing chromosome number Phase II Meiosis II separating sister chromatids o o o o Meiosis I Reduction division Prophase I Longest most complex phase Leptotene zygotene pachytene diplotene diakinesis Chromosome pairing homologous pairing Crossing over syaptonemal complex chiasmata bivalent tetrad o Chiasma exchange of DNA strands has occurred Can visually see the crossing over chiasma Crossing over chromosome shuffling variation generation Metaphase I Homologous pairs along midline Kinetochores attached to one pole Chance alignment relative to poles underlies genetic principle of Cohesion keeps sister chromatids together regulating cohesion is Independent Assortment key to successful meiosis Anaphase I Telophase I o Meiosis II Separation of sister chromatids Prophase II condensation Metaphase II Centromeres along midline Kinetochores attached to each pole underlies genetic principle of Segregation Anaphase II Chromatids to opposite poles Cohesion again plays a role Telophase II o Meiosis is the basis of all sex key concept Variations in some details among organisms Polar bodies in humans an others Products of meiosis might undergo simple or complx development before producing gametes for fertilization eg flowering plants Alternate Theories of