The Mitochondrial Free Radical Theory of Aging - Supernova: Pliki

An Introduction to Mitochondria
Fig. 2.2. A mitochondrion. For clarity the cristae are not shown; only items
discussed in this book are noted.
amount of DNA, which will be described in detail in Section 2.4, and the machinery
(including ribosomes) for decoding that DNA.
The matrix is one of the most alkaline environments in the cell. It has a pH of between
8 and 8.5, roughly half a unit higher than the cytosol.
2.2.4. Composition of the Inner Mitochondrial Membrane
I mentioned above that the inner membrane is impermeable to most molecules.
However, that only means that most molecules cannot freely pass through it. Many molecules
do indeed pass through, under the active control of proteins embedded in the membrane.
These proteins are very specific—each one transfers only a particular molecule, one at a
time. This rigid control exists because it is vital for mitochondrial function; the molecules
that are transported in this way must be transferred when they are needed, but only in the
right quantity, and without attendant, unregulated transfer of other molecules.
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