Mitosis lab
Looking at the onion root slide, locate 50 cells that appeared to be actively dividing when the slide was made. Notice how these cells are arranged in columns. This will allow you to easily keep track of them while you are doing this activity.
For each of the 50 cells you chose, identify which stage of mitosis the cell is in, and keep track using the “tally marks” section of the table below.
Once you have tallied 50 cells, count how many were present for each phase of mitosis and write that number in the “count” section of the table.
Which phase had the most cells? __________________________
Which phase had the least cells? ________________________
Calculate the percentage of cells found in each phase. This can be done by dividing the number of cells in the phase by 50, which is the total number of cells in the count, and then multiply your answer by 100. Enter this number in the “percentage” section of the table.
The percentage of cells found in each phase is a measure of how long each phase lasts. For example, if 25 percent of the cells are in prophase, then prophase takes 25 percent of the total time it takes for a cell to undergo mitosis. Mitosis in onion cells takes about 80 minutes.
Calculate the actual time for each phase using this information and the percentage you have just determined. Use the following equation to find the duration of each phase of mitosis in onion cells. Enter the time (in minutes) of each phase under the “Time (in minutes)” column of the table.
