Download Time for Mitosis Lab

Virtual Mitosis Lab
Onion Root Tip
Mitosis is considered to be a nuclear division, since its main phases deal strictly with the
nucleus and its contents (DNA). Mitosis consists of four major phases: prophase, metaphase,
anaphase, and Telophase. Mitosis is part of a larger cycle called the cell cycle. When a living
organism needs new cells to repair damage, grow, or just maintain its condition, cells undergo
the cell cycle. In this lab you are going to determine the approximate time it takes for a cell to
pass through each of the four phases of mitosis.
Go to the following site:
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html
Drawings of the Interphase and mitosis
Use the circles below to draw cells in interphase and in each phase of mitosis.
I
P
M
A
T
Start reading the online “Onion Root Tips” from the URL listed above. You need to follow the
directions given to you on the website. As you proceed in the lab, you will be sorting virtual
onion root tip cells into their current phase. Count the number of cells that you see in each
phase and record answers in the table below. Complete the table.
Table1: Relative Duration of Each Phase of Mitosis
Phase Name
Count
Percentage*
Time*
(minutes)
INTERPHASE
Prophase
mitosis
Metaphase
Anaphase
Telophase
*see instructions on the next page
Total number of cells in sample - _________
Total number of cells undergoing mitosis in the sample - ___________
To find percentage:
Calculate the percentage of the cells found in each phase of mitosis. Dividing the number of
cells in each phase by the total number of cells going through mitosis; then multiply by 100.
Record your data in Table 1.
To find time (minutes):
In this lab, you can base your calculation on a total cell cycle of 24 hours. Of those 24 hours, it
takes about 80 minutes to go through mitosis. Calculate the actual time for each mitotic phase
by taking your percentage of the phase and dividing it by 100 and then multiplying that by 80
minutes. Record your data in table 1.
Duration of mitosis (in minutes) = percentage
__________
X 80 minutes
100
Conclusion:
1. The cell cycle is typically divided into (choose one):
a) cell growth, division of the nucleus, division of the cytoplasm
b) prophase, metaphase, anaphase, telophase, cytokinesis
2. The cells that you are observing come from an onion root tip. Why do you think that cell
division would be easily seen here? ___________________________________________
________________________________________________________________________
3. How many phases is mitosis divided into? ______________
4. According to the lab, which phase of mitosis takes the longest to complete?
_________________
5. Which phase of mitosis requires the next longest time to complete? ________________
6. What important changes are occurring in the nucleus of the cell during the longest phase of
mitosis? _______________________________________________________
7. Which phase requires the shortest time to complete? _________________
8. How many cells are there at the end of cytokinesis? ______________
9. Why are there so many cells in Interphase? _____________________________________
________________________________________________________________________
10. DNA is copied during which part of the cell cycle? _________________