Instructions:
In this exercise you will observe the cells of an onion root where growth is active. This provides an opportunity to see the stages and cellular features of mitosis. To observe the preparation of an onion root tip as well as an explanation of how to recognize the cellular features of the mitotic phases go to:The Mitotic Index Root Tip Squash from Biology Practicals and Revision Biology Tutor
Then use the image produced of onion root tip cells below to draw interphase and the phases of mitosis in your Mitosis Lab Report.doc. Answer the questions regarding the phases of mitosis in your lab report before moving on to Exercise 2.
Exercise 2 – Recognizing the Phases of Mitosis and Calculating the Time Spent in Each Phase
In this exercise, you will be presented with cells from the tip of an onion root. You will classify each cell based on what phase it is in. At the end you will count up the cells found in each phase and use those numbers to predict how much time a dividing cell spends in each phase. You can base your calculation on a total cell cycle of 24 hours. To complete this exercise, go to: The Biology Project hosted by The University of Arizona (Links to an external site.) and record your data in the Exercise 2 Table in your lab report. After you have completed the exercise, calculate what percentages of the cells were in each phase and then apply those percentage to the 24 hour time frame to estimate how much time was spent in each phase.