1. Mitosis

A. This part of the lab is based on an activity produced by the Biology Project, found at http://www.biology.arizona.edu/cell bio/activities/cell cycle/cell cycle.html. Please go to that site, read the page and then click on Next at the bottom of each page until you have read the entire lab and completed the activity. Count the number of cells that you find in each of the phases of the cell cycle, and complete the table below. Use it to answer the rest of the questions.

For the last row, assume that the total amount of time required for the cell cycle is 24 hrs, and determine how long a cell stays in each stage based on the percentage of cells found in each phase.

B. The mitotic index is the proportion of cells in mitosis out of the whole sample. To get the mitotic index, add together all phases of mitosis (not interphase) and divide by the total number of cells.

What is the mitotic index for this sample?

C. Questions. Use complete sentences, at least one paragraph per answer, and do not copy and paste answers. USE YOUR OWN DATA!! Don’t look it up somewhere, use the data you generated above.

1. Which is the longest part of the cell cycle? What happens during that stage? Why do you think it is the longest?

2. Which is the longest phase of mitosis? What happens during that stage? Why do you think it is the longest?

3. Which is the shortest phase of mitosis? What happens during that stage? Why do you think it is the shortest?

4. How do you think the mitotic index of cancerous tissue would compare to that of normal tissue? Explain.

5. How do you think a drug that prevents spindle formation would affect mitosis? Would this be useful as a cancer drug, do you think? Why or why not?

6. One type of cancer drug stops cells from making DNA nucleotides. Specifically, what effect would that have on the cell? What effect would it have on the body?

II. Meiosis

A. Rearrange the pictures below into the proper order for meiosis, and identify each stage by stage name and number (i.e. metaphase I for the first metaphase, and metaphase II for the second metaphase). Note that there are only 8 pictures so not all stages are present. Write the names in the textboxes after you have rearranged the pictures.

B. Using X’s to represent doubled chromosomes (sister chromatids), l’s to represent single chromosomes, and lines for the spindle, diagram the following stages of meiosis. Use red to indicate paternal homologs and blue to indicate maternal ones. The cell has N=2 (2 different types of chromosomes, but they don’t have to look different in your diagram). Put the chromosomes and spindle in their proper arrangements in the textboxes.