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What do membranes of mitochondria look like? 
Only the
high-power magnification of an electron microscope makes
membranes of mitochondria visible.
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The picture on the right shows a mitochondrion. It is oval shaped and surrounded
by a double membrane, much like the cell membrane. Inside are
many membranes that anchor the proteins that help trap
chemical bond energy of pyruvic acid in phosphate bonds. |
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Why
do cells need mitochondria?
Cells
have to get energy from somewhere. We know that we get our energy
from the food we eat. We are not like plants that can make materials
and energy from sunlight, water and carbon dioxide. But how
does food produce energy? Food is digested (broken down) into small
enough molecules that can be absorbed into the blood from the
intestine. Chemical reactions in the body make many of those
molecules into the energy source known as glucose. Glucose is
a 6-carbon sugar.
The whole process of burning foodstuffs is
called "oxidative metabolism." It involves three series of reactions:
- Glucose conversion to pyruvic acid.
- Pyruvic acid conversion to carbon dioxide
and water.
- Oxygen reactions that store energy for cells.
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