AP 5069 L03 MitosisAndMeiosis

Pre-Lab Questions What are chromosomes made of? Compare and contrast mitosis and meiosis. How does mitosis differ in plant cells versus animal cells? Cancer is a disease related to uncontrolled cell division. Investigate two known causes for cancer and use this knowledge to invent a drug that would prevent the growth of cancer cells. Experiment 1: Observation of Mitosis in a Plant Cell Data Tables Table 1: Mitosis Predictions Predictions Supporting Evidence Table 2: Mitosis Data Image Stage Number of Cells in Stage Total Number of Cells Calculated % of Time Spent in Stage Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Table 3: Stage Drawings Cell Stage Drawing Interphase Prophase Metaphase 1607820-3238500 Anaphase 153162059983 Telophase Cytokinesis Post-Lab Questions Label the arrows in the slide image with the appropriate stage of the cell cycle. A _______ Interphase ____________ B _______ Metaphase ____________ C _______ Interphase ____________ D _______ Telophase ____________ E _______ Prophase ____________ F ________ Anaphase ___________ In what stage were most of the onion root tip cells? Does this make sense? Most of the onion root tip cells are in interphase. It makes sense because a cell spends most of its time in the interphase stage. As a cell grows, what happens to its surface area-to-volume ratio (hint: think of a balloon being blown up)? How does this ratio change with respect to cell division? What would happen if mitosis were uncontrolled? How accurate were your time predictions for each stage of the cell cycle? Discuss one observation you found interesting while looking at the onion root tip cells. Experiment 2: Following Chromosomal DNA Movement Through Mitosis Cell Cycle Division: Mitosis Beads Diagram Prophase: There are 4 chromosomes. Metaphase: There are 4 chromosomes. Anaphase: There are 8 chromosomes. Telophase: There are 8 chromosomes. Cytokinesis: There are 4 chromosomes in each of the new cell. Post-Lab Questions Why are chromosomes important? What information do they provide? How many chromosomes did each of your daughter cells contain? How often do human skin cells divide? Why might that be? Compare this rate to how frequently human neurons divide. Is there a difference? Why might that be? Experiment 3: Following Chromosomal DNA Movement Through Meiosis Cell Cycle Division: Part 1 – Meiotic Bead Diagrams (Without Crossing Over) Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Cell Cycle Division: Part 2 – Meiotic Bead Diagrams (With Crossing Over) Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II Post-Lab Questions What is the state of DNA at the end of meiosis I? What about at the end of meiosis II? Why are chromosomes important? How are meiosis I and meiosis II different? Why do you use non-sister chromatids to demonstrate crossing over? What combination of alleles could result from a crossover between BD and bd chromosomes? How many nuclei are present at the end of meiosis II? How many chromosomes are in each? Identify two ways that meiosis contributes to genetic recombination. Why is it necessary to reduce the number of chromosomes in gametes? Blue whales have 44 chromosomes in every cell. Determine how many chromosomes you would expect to find in the following: Sperm Cell Egg Cell Daughter Cell from Mitosis Daughter Cell from Meiosis II Research and find a disease that is caused by chromosomal mutations. When does the mutation occur? What chromosomes are affected? What are the consequences? Diagram what would happen if sexual reproduction took place for four generations using diploid (2n) cells. Experiment 4: Crossing Over Data Tables Table 4: Sodaria fimicola Crossover Data Image Number of Crossovers Number of Non-Crossovers Image 1     Image 2     Image 3     Post-Lab Questions Determine the percentage of crossovers. To do this, divide the number of crossovers by the total number, and multiply it by 100. Determine the map distance. To do this, divide the percentage of crossover by two. Note that the number is divided by two because crossover occurs once between two chromosomes. Experiment 5: The Importance of Cell Cycle Control Data 1. 2. 3. 4. 5. Post-Lab Questions Record your hypothesis from Step 1 here. What do your results indicate about cell cycle control? Suppose a person developed a mutation in a somatic cell that diminishes the performance of the cell’s natural cell cycle control proteins. This mutation resulted in cancer but was effectively treated. Is it possible for this person’s future children to inherit this cancer-causing mutation? Why or why not? Why do cells that lack cell cycle control exhibit karyotypes that look physically different than cells with normal cell cycle control? What are HeLa cells? Why are HeLa cells appropriate for this experiment? Research the function of the protein p53. Explain how changes in p53 activity may affect cell cycle control. What is the Philadelphia chromosome? How is this chromosome related to cancer? Identify how this chromosome appears physically different on a karyotype than it appears on a karyotype of normal chromosomes.