Mitochondria Observation – from AP Bio ListServ -
MITOCHONDRIA IN CELERY
Mitochondria may be observed in living cells with the aid of a vital stain called Janus Green B. This stain
is colored when it is an oxidizing agent. When the mitochondria are actively engaged in cellular
respiration (oxidzation of sugar), the stain acts as a hydrogen acceptor and becomes reduced and
colorless. The Janus Green B will stain the mitochondria right away, but as you watch over a few minutes,
the stain will fade.
Obtain 2 razor blades and 2 coverslips. Place one razor blade on the lab bench and place one coverslip
on each end so the coverslips barely stick out past the sharp edge of the blade. Place the other razor
blade on top of the coverslips so you have a space between the sharp edges that is one coverslip thick.
Tape the two razor blades together securely with white tape
Obtain a celery stalk, and place it on the lab bench so it is stable.
Position the razor apparatus firmly over it and make a slice. You should have a thin slice of celery that is
no thicker than the coverslip.
Place the slice on a glass slide with two drops of sucrose solution, and put a clean coverslip over it.
Observe the celery cells under the compound microscope. Find a section of the celery thin enough to
observe the chloroplasts, and even a clear nucleus (you can stain the celery with methylene blue, another
vital stain to see the nucleus clearer, but do not do this until you have finished this exercise!)
Place a piece of filter paper on one side of the coverslip so it begins to soak up the sucrose. At the same
time, place 2-3 drops of Janus Green B at the opposite side of the coverslip. The filter paper will draw the
stain across the celery. Watch the cells, and the mitochondria (very small spots) in the cells should take
on a blue/ green color. Observe what happens for a few minutes
Students can design labs (alter pH, sugar concentrations, CO2). One student rad that Rotonone was
suspected as a mitochondrial inhibitor and investigated that; won science fair
CLARIFICATION on Razor Blade Set Up
Get a double edge razor blade and lay it on the table. Lay a cover slip on it so that one of the sharp edges
is exposed and the other covered. Put a second slip next to that one. This will expose a sharp edge and
protect the other. Then place a second blade on top of the first. Tape the glass exposed edge to hold
everything in place and protect your fingers. This will give you a device with two cutting edges that will
allow you to cut very thin (one cover slip in thickness) sections.