Who killed Yew? Murder and Mitosis Part 1: 1. What type of plan could be carried out by adding the seeds of Taxus baccata to a pecan pie? - This would be an intoxication type plan. A pecan pie has no levels of toxicity at all unless someone is allergic to pecans. Yet, seeds of the Taxus baccata are toxic to humans. The addition of such will intoxicate someone. 2. What are taxines? - They are chemicals found in Yew plants that are toxic because they disrupt mitosis. Part 2: 1. Most of the governor’s lunch party just ate pecan pie filled with taxines, a potent mixture of poisons, one of which is actually a powerful mitotic inhibitor. What is a mitotic inhibitor? - It is a drug that is derived from natural plant sources that hinders the process of mitosis (cell division) 2. Which specific cytoskeletal element is most susceptible to mitotic inhibitors? - The specific cytoskeletal element most susceptible is the microtubules because they are the largest cytoskeletal filament. 3. Describe the function of mitosis in animal cells. Why is mitosis important? - Mitosis is important because it is required for growth and repair in the body.Mitosis in mammals is responsible for somatic or body cell division. This is how cells replicate to repair damaged tissues or make need tissues for the sake of growth. 4. In the table below, draw the six major stages of the cell cycle. Be sure to label the following in each of your drawings where appropriate: chromosomes/chromatin/sister chromatids, mitotic spindle, asters, centromeres, microtubules, kinetochore, cleavage furrow, and nuclear membrane. (DO NOT NEED TO DRAW) - Prophase: nuclear membrane begins to break down, separation of duplicated centrosomes, assembly of mitotic checkpoint at centromeres - Metaphase: chromosomes align on a central plate, assembly of microtubules to form mitotic spindles, microtubules capture both centromere regions of a chromatid pair results in checkpoint silencing. - Anaphase: spindles pulling apart, separating sister chromatid pairs - Telophase: chromosomes reach their poles, re-forming of nuclear membrane, chromosomes condensation, cytokinesis. 5. In each stage, note the role of the microtubules. - Prophase: centrioles move to opposite poles of the cell and start sending out microtubules - Metaphase: assembly of microtubules to form mitotic spindles, microtubules capture both centromere regions of a chromatid pair results in checkpoint silencing. - Anaphase: play a role in the migration of chromosomes to opposite ends of a cell - Telophase: is also marked by the dissolution of the kinetochore microtubules and the continued elongation of the polar microtubules Part 3: 1. Why did Dr. Beckham has only mild symptoms (dizziness, nausea, racing heart beat) as compared to the others? - This is probably because she didn’t ingest that much Taxus Baccata. The small portion ingested caused those mild symptoms. Part 4: 1. Based on the video you just watched, explain how paclitaxel exerts its effect and why that could be deadly. Specifically discuss the role of microtubules during mitosis and how that is impacted when a cell is exposed to paclitaxel. - Paclitaxel works by inhibiting mitosis. It interferes with the normal breakdown of the microtubules that regulate the process and cause apoptosis because the cell receives a signal to undergo apoptosis. Paclitaxel begins to impact the microtubule function after metaphase and before anaphase. It prevents the microtubule from shortening, which prevents sister chromatids to pull apart. 2. Generally speaking, what is cancer? Why would the discovery of paclitaxel’s mechanism of action be exciting for scientists studying cancer? - Cancer is a condition that is caused by uncontrollable cell division in many different parts of the body.Since paclitaxel disrupts cell division, researchers studying cancer could find a way to use Paclitaxel to reduce cancer in cancer victims and they could also find out a way to use Paclitaxel to make a cancer vaccine or remedy. 3. There are three major types of cancer treatments: surgery to remove cancerous tissue, chemotherapy, and radiation. Which treatment would paclitaxel be considered? - Chemotherapy 4. List at least two organs in the body with rapidly dividing cells. - Skin - GI tract 5. Chemotherapeutic drugs are toxic to any rapidly dividing cell and are typically administered into the circulatory system. Paclitaxel has been converted to a powerful and commonly prescribed chemotherapy known as Taxol®. What would be side effects on healthy tissue, particularly those discussed in Question 4 (above), after being exposed to Taxol ? - These tissues may die. 6. Why does ingesting parts of the yew tree cause death while administration of the chemotherapy drug Taxol does not? Do you think cancer patients could be given chemotherapeutic drugs indefinitely? - Chemotherapy is taken out of the Yew tree, but those who extract it particularily just take the paclitacel part and reject the poisionous. I think chemotherapy will be a primary treatment option until there is a more beneficial option.