Download Lab Instructions - The Great Divide

DO NOT WRITE ON THIS LAB!!!!!
LAB # ______
Lab Instructions – The Great Divide
Purpose: to locate and identify stages of mitosis in prepared slides of onion root tips.
Background: Mitosis is the division of nuclear material so that each new cell contains the
same genetic information as the original cell. Mitotic cells are found in actively growing
tissues such as onion root tips. Stages of mitosis can be distinguished by position of the
chromosomes, thickness of the chromosomes, and the presence or absence of a nucleolus,
a nuclear membrane, and spindle fibers.
Materials:
Diagram of mitotic stages
Compound microscope
Prepared slide of onion root rips, longitudinal section
Procedure:
A. Under low power, scan the slide of an onion
root tip. Look for the region of small,
actively dividing cells (See Fig. 1).
B. Switch to high power, focus using your fine
adjustment knob, and adjust the
illumination if necessary.
C. Locate cells that resemble the stages shown
in your plant mitosis diagrams. Observe at least one
cell in each of the following stages: interphase,
prophase, metaphase, anaphase, telophase.
D. Draw a picture of what you can actually see in the
microscope. Put only the details in that are actually
visible on your microscope.
E. Answer the questions in the observation section.
Figure 1: Region of actively growing cells.