The cell cycle, or cell-division cycle, is the series of events that takes place in a cell leading to its division and duplication or replication. The cell-division cycle is a vital process by which a single-celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed.
Prokaryotic cells, those without a nucleus, the cell cycle occurs via a process termed binary fission. Eukaryotic cells, those with a nucleus, the cell cycle can be divided in two periods:
1. Interphase —during which the cell grows, accumulating nutrients needed for mitosis and duplicating its DNA and organelles, and
2. Mitosis (M) phase or Cell Division, during which the cell splits itself into two distinct cells, often called "daughter cells.” The final phase, Cytokinesis, completes the cell division process.
This activity asks students to categorize mitosis slide images and determine the relative length of time that an onion cell spends in interphase, prophase, metaphase, anaphase, and telophase/cytokinesis. In the past, I have had my students complete this by using the actual microscopes; however, it is very tedious work and very difficult for some. I developed this activity to mimic what students do under the microscope - but is much easier, and will be helpful for those students who struggle. For those students who need more of a challenge, this activity can be used as a pre-requisite for completing the same sort of task with the microscope.