Mitosis Blog Report

For this lab activity, we used microscopes to examine the different stages of cells. We examined two materials: whitefish blastula and onion root tips. First we located the whitefish blastula under the microscope using a 10x lens. Once we found it, we used a 40x magnification lens to zoom in closer to the individual cells.

The whitefish was full of cells in different stages of the mitosis, majority being interphase. The cell circled in green is in metaphase because the chromosomes are lined up in the center of the cell. The one circled in red is in early anaphase because the chromatids have started to move to opposite sides of the cell. The one in blue is telophase because the cell has started to pinch itself in half. I never knew how easily you could see the individual spindle fibers without a high power microscope.

Next, we moved on to onion root tips. We followed the same steps of finding it with 10x and zooming in with 40x.

Again, almost all the cells were in interphase, except a few along the side of that arrow that were in late anaphase.

For the next part of our experiment, we estimated the relative length of time that a cell spends in the different stages of cell replication. For this part, we only studied the onion root tip. We were told that the length of the cell cycle is approximately 24 hours for onion root tips. First, we counted the number of cells in each stage in two fields of view. Using that information, we calculated the percent of the total cells are in each stage, and then multiplied that number by 24 hours (1,440 mins). By doing so, we estimated the amount of time the cells spend in each phase. Our data is recored below:

Analysis: 

1. It is more accurate to call mitosis "nuclear replication," rather than "cellular divison," because the nucleus isn't dividing, it is replicating.
2. Whitefish blastula and onion root tip are selected for a study of mitosis because these cell tissue types are known to have rapid cell division rates. Also light can pass through them easily, allowing them to be viewed with a light microscope. 
3. If my observations had not been restricted to the area of the root tip that is actively dividing, my results would have had only cells in interphase, which makes me wonder if the root tip we observed are beginning to stop dividing and thus have mostly cells in interphase. 
4. Based on my data, I can infer that, starting with interphase, each stage is dramatically shorter than the previous one, except for anaphase and telophase.