Name: ___________________________________                Block: ____________

Cell Cycle Lab

Mitosis is the process of how eukaryotic cells divide and replicate. The process results in two cells with identical DNA.  In most cells this is a short proportion of the overall cell’s existence, approximately 10%.  The cell cycle is divided into different stages with those particular to cell division defined as the Mitotic phase.  By observing stained cells, these stages can be observed in a eukaryotic plant cell.

When using the microscopes make sure to never use coarse adjustment while on medium or high power and to check the diaphragm and fine adjustment if you are having trouble finding or focusing on the specimen.


In this lab, you will draw and label a prepared of onion root tip that has been stained to highlight chromosomes undergoing mitosis  Each slide contains multiple portions of onion root tip which each contain hundreds of cells.  Thus, you will need to move the slide around and search for each of the different stages of mitosis.


When completing your drawings, ensure the following:

Part A: Interphase

Part B: Prophase

Part C: Metaphase

Part D: Anaphase

Part E: Telophase

Part F: Mitotic Index

The Mitotic index is a measure for the growth of a cell population or as the ratio between the number of cells in mitosis and the total number of cells.  The mitotic index can be an important factor in predicting overall survival and effectiveness of chemotherapy; cancerous cells divide at a higher rate, therefore, more cells in the stage of interphase would suggest a higher effectiveness of chemotherapy.

Using your Onion Root Tip slide, move the slide to an area close to the tip of the root; focus on high power.  Without moving the slide, count the number of cells in interphase and each stage of mitosis and record below.  Turn in your data here and view the class data here.

Data Table 1: Proportion of Mitosis Stages in Onion Root Tip Cells

Stage of Mitosis

Total Number of Cells






Total Cells in Stages of Mitosis:

Total Cells Observed:

Conclusion & Evaluation:

  1. Calculate the mitotic index for the class data, found here.

  1. How does the length of each portion of the cell cycle compare?  

  1. Explain the products that are produced through Mitosis.

  1. Discuss the differences between interphase and stages of cell division.


Lab Standard: Analysis



Nearly Meets


A full explanation of the lab standard rubric can be found here