1. PowerPoint Breakdown:<br />Slide 2: Though it appears blank, this is where I would play the clip from Twilight. Afterwards, I'd ask the students questions, what were Bella and Edward studying (mitosis, which is something we've studied previously). What is mitosis (creating daughter cells with the same chromosome cell). How does the study of mitosis in Twlight forshadow the genetic differences between humans, vampires, and werewolves (Humans = 23 pairs chromosomes, Vampires = 25 pairs, Werewolves = 24 pairs). Where does each chromosome in the pair come from (one from dad, one from mom). How do their chromosomes come together (sex). Specifically, how (sperm + egg). Does anyone know how the sperm and egg are formed (meiosis).<br />Slide 3: Review of terms previously learned: Diploid = two sets of chromosomes (emphasize di = 2); Homologous = same/matching pair (emphasize homo = same); Haploid = 1 set of chromosome. Ask students, the daughter cells from mitosis are what (diploid). The sperm or egg cells from meiosis are what (haploid).<br />Slide 4: Discuss that meiosis is just mitosis that occurs twice<br />Slide 5: Discuss what happens when meiosis does not occur correctly. Ask students to identify what disorders the people in the pictures have (Down's Syndrome, Kleinfelter's Syndrome, Willi-Prader Syndrome, Trisomy 22 (cat-eye syndrome). All of these occur from nondisjunction (breakdown the word, first from student ideas, then with guidance as needed: junction = meeting place, dis = apart, disjunction = break apart meeting place, nondisjuction = meeting place is not broken up)<br />Slide 6 - 13: Pass out cue cards to students - 8 Chromosome 1, 8 chromosome 2, 8 chromosome 3, 2 centrioles, 4 spindle fibers. Have students act out the phases of meiosis in sperm cells (walk through). Prophase I: Have students form a tetrad (emphasize tetra = four, associate with tetris blocks) for each chromosome by having all those with chromosome 1 (and 2 and 3) to join hands so that they are forming an quot;
Xquot;
; centrioles in correct position with spindle fibers. MetaphaseI: Have students line up down the middle of the room, attached to spindle fibers. Anaphase I: Tetrads separate to opposite ends of the cell (classroom). Telophase and cytokinessis I: I walk down the middle of the room telling them that they are now in two different cells. From there, we go through PMAT II, and now there are four cells that contain a quarter of the tetrad. Beacause they are sperm, all four cells get to live. Then have the students act out the phases of meiosis in egg cells (by themselves). At the end, because they are forming an egg cell, three of them will die.<br />Slide 14 and 15: Talk about which sex is a limiting factor in the population. Discuss in terms of how many sperm cells get to live verses how many egg cells.<br />Slide 16: Look at picture representation of meiosis and mitosis - have students pick out the difference (tetrads, PMAT, etc)<br />Slide 17: Briefly discuss gene linkages. Main point = Morgan, not Mendel discovered it! Have students recall how they formed their tetrads. What would have happened if they would have formed it differently, with a different partner (the genes in the chromosome would have been different). What does this mean (blue eyes instead of brown eyes, dark skin verses light skin, blonde hair verses brown hair). These differences occur due to crossing over, which is due to how the tetrads are formed and how they separate<br />Slide 18: Show students what a gene map looks like. Discuss how the closer together the genes are, the more likely they will stay together (i.e. if one gene is located on their elbow and another on their wrist, we're not going to break their arm to separate the gene. However, if one gene is located on your partner's elbow and one on your wrist, it will - recall demonstration)<br />