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Biology 11 – The Study of Mitochondria
Background: Mitochondria are the power sources of the
cell. In most non – photosynthetic eukaryotic cells, 90%
of the ATP is formed in the mitochondria. Mitochondria
have a double membrane, the inner one is convoluted in
many folds called cristae. Some of the energy-producing reactions of cell
respiration take place in the fluid that fills the interior of the mitochondria,
others are carried out by the enzymes that form a part of the surface of
the cristae.
Purpose: To observe the structure of mitochondria and to understand its
role in cell respiration.
Materials: Microscope, microscope slides, cover slip, single edge razor
blade, medicine dropper, fresh celery stalk, 5% glucose solution.
Procedure:
1. Shave a very thin section from the end of a celery stalk. Try to
avoid the vascular bundles.
2. On a clean glass slide, place a drop of 5% glucose solution and place
the celery section on the liquid.
3. Place a cover slip over the specimen. You may have to push the
cover slip down. Wipe excess moisture from your slide.
4. Observe your specimen under low power. Move your slide to locate
a single layer of cells(try closing the diaphragm).
5. Switch to medium and then to high power and try to find the tiny
mitochondria as they move.
6. (a) What cellular structures can be seen at this
time?______________________________________
(b) Describe the mitochondria.
____________________________________________________
_____________________________________
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7. Draw and label a single cell on high power in the space below. Make
sure that all diagram rules are followed.
Conclusions and Analysis Questions:
1. Why was the sugar solution needed to demonstrate the function of the
mitochondria?
2. Describe in detail the purpose of the mitochondria.
3. Would you expect to find mitochondria in bacterial cells? Give reasons to
back up your answer.
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Advanced Students please go to http://science.howstuffworks.com/femaleancestor1.htm , to answer the following questions about mitochondria:
1. How does mitochondrial DNA differ from nuclear DNA?
2. Explain the term recombination.
3. What happens to the mitochondria found in the sperm cells?
4. Why is mitochondrial DNA said to be matrilineal?