Download Investigation 7 Cell Division

Investigation 7 Cell Division: Mitosis AP Biology How do eukaryotic cells divide to produce genetically identical cells? ! Lab Write Up: Title, Date, Partners, Purpose (read through the lab to determine the purpose) ! Lab Write Up: Headings and answer the following questions – Use complete sentences Getting Started Questions 1. How did you develop from a single-­‐celled zygote to an organism with trillions of cells? 2. How is cell division important to a single-­‐celled organism? 3. What must happen to ensure successful cell division? 4. How does the genetic information in one of your body cells compare to that found in other body cells? 5. What are some advantages of asexual reproduction in plants? 6. Why is it important for DNA to be replicated prior to cell division? 7. How do chromosomes move inside a cell during cell division? 8. How is the cell cycle controlled? What would happen if the control were defective? Procedure Part 1: Modeling Mitosis You will investigate mitosis using models and a website. Use the template on the last page of this handout to model mitosis with pipe cleaners and beads. Go to the website: www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html and complete the activity by " Creating a data table as described " Identifying the stage of cell division for each cell " Completing the data table by count cells in each stage and calculating percentages. ! Lab Write Up: Heading, Date table, Answer the following questions using complete sentences Mitosis Questions: 1. If a cell contains a set of duplicated chromosomes, does it contain any more genetic information than the cell before the chromosomes were duplicated? 2. What is the significance of the fact that chromosomes condense before they are moved? 3. How are the chromosome copies, called sister chromatids, separated from each other? 4. What would happen if the sister chromatids failed to separate? Procedure Part 2 Using prepared mitosis onion root slides and a compound microscope, 1. Observe the cells at high magnification (400-­‐500 X) 2. Within the field of view, count the cells in each phase. Repeat the counts in two other root tips. 3. If you have difficulty using a microscope to count the cells, use the photo index cards of mitosis. 4. Collect the class data for each group, and calculate the mean and standard deviation for each group (see next page for instruction on calculating standard deviation). You must make a table in your notebook for class data. 5. Compare the number of cells from each group in interphase and in mitosis. Table 1. Onion Root Tip Cell Phase Data Number of Cells Tip Interphase Mitotic Total 1 2 3 Total Percent ! Lab Write Up: Table of each phase, Class Data Tables for each group, Calculations, Class Data Table with mean and standard deviation (see below) Calculate Standard Deviation σ=
∑( x − x)
n −1
2
1. Find the class mean for percent time in mitosis. 2. Subtract each group’s results from the mean. 3. Square each of the differences from above. 4. Add the square value of the € differences and divide by the number of groups. 5. Take the square root. ! Lab write up: Heading, calculations, results, answer the following questions, and write a conclusion Analysis Questions 1. What was the importance of collecting the class data? 2. Was there a significant difference between the groups? How do you know? 3. Would an increased number of cells in mitosis mean that these cells are dividing faster that the cells in the roots with a lower number of cells in mitosis? Conclusion: Heading, summarize what you did, your results, your expectations, and expand.