556 1-800-452-1261
Make Mitosis Slides
The process of growth and division in a typical eukaryotic cell is called the cell
cycle and is composed of two phases—interphase and the mitotic (M) phase.
Each cell cycle begins with the formation of a new cell and continues until
that cell divides into two offspring cells. Each offspring cell then begins the
cycle again. In the apical meristem region of an onion root tip, one complete
cell cycle is typically completed in approximately 24 hours. Of that time,
between 2–4 hours is spent in the mitotic
phase of nuclear and cellular division.
Mitosis is subdivided into five
phases. During prophase, the nucleolus
fades, chromatin condenses
into chromosomes, and cytoskeleton
microtubules create the spindle
fibers necessary for chromosome
separation. In prometaphase, the
nuclear envelope breaks down so there
is no longer a recognizable nucleus, and
spindle fibers elongate. During
metaphase, the chromosomes
reach a position called the
metaphase plate, which is
midway between the poles.
At the onset of anaphase, the
sister chromatids also separate,
splitting the chromosome in
half. The spindle fibers shorten
and drag the attached half
chromosomes, or chromatids,
to opposite poles of the cell.
In telophase, the chromatids
arrive at the poles and the spindle fibers that have pulled them apart disappear.
A nuclear envelope reforms around each cluster of chromosomes, and
these chromosomes return to their more extended form while cytokinesis
begins.
Materials Required
• Hydrochloric acid solution, 1 M • Cup • Pencil with eraser • Methylene blue stain solution, 1%
• Forceps • Pipets, 3 • Water, deionized and tap • Microscope slides, glass
• Ruler • Compound microscope • Onions, bulbs or green • Scalpel
• Cover slips • Paper towels
Procedure
1. Wear chemical splash goggles and chemical-resistant gloves.
2. Cut three roots from an actively growing plant using a scalpel.
Caution: The scalpel is extremely sharp.
3. Trim the tip of each root to 1 cm; use only the tapered end of the root
tip.
4. Use forceps to place 2–3 root tips (use only the 1-cm tips) on a glass
microscope slide.
5. Using a clean, graduated pipet, add 2–3 drops of 1 M hydrochloric
acid to cover the root tips on the microscope slide.Note:
Hydrochloric acid is corrosive to skin and eyes.
6. Allow the root tips to soak in the acid for 5 minutes. After 5 minutes,
use a paper towel and carefully blot away excess hydrochloric acid
from the slide. Caution: Avoid contact of the acid with skin.
7. Using a clean, graduated pipet, add 2–3 drops of deionized water to
the root tips.
8. Use a paper towel to blot away excess water.
9. Repeat steps 7 and 8.
10. Using a clean, graduated pipet, add 2–3 drops of methylene blue
stain to the root tip. Note: Methylene blue stain is a permanent
stain.
11. Allow the root tips to soak in the stain for 3 minutes. Use a paper
towel to blot away excess methylene blue stain.
12. Add 1 drop of deionized water to the root tips.
13. Use forceps to move one root tip to a clean microscope slide.
14. Place a cover slip on the root tissue. Using the eraser end of a
pencil, gently apply pressure on the cover slip to squash the root
tissue. Apply an even downward pressure on the tips and cover slip
but not so hard as to break the cover slip. Do not twist or grind the
cover slip.
15. Using low magnification on the microscope, focus on the root cells.
Switch to medium power or high power as necessary to easily visualize
the inside of the onion root cells.
16. Study all of the squashed tissue to locate cells in each stage of the
cell cycle. Note: All stages of mitosis may not be present within a
single field of view.
Materials are Available from Flinn
Catalog No. Description Price/Each
H0013 Hydrochloric Acid Solution, 1 M, 500 mL $ 6.80
M0074 Methylene Blue Solution, 1%, 100 mL 5.96
FB1468 Onion Bulb Sets, Pkg of 100 14.57
ML1381 Microscope Slides, Glass, Pkg. of 72 11.49
ML1383 Cover Slips, Glass, No. 1, 22 x 22 mm, Pkg. of 200 10.91
/?type=All&defaultType=Products&query=H0013
/?type=All&defaultType=Products&query=M0074
/?type=All&defaultType=Products&query=FB1468
/?type=All&defaultType=Products&query=ML1381
/?type=All&defaultType=Products&query=ML1383
/slide.No