Figure 19.6 The peroxisomes (electronic micrograph)

The mitochondria. the mitochondria have two membranes: an external mitochondrial membrane and an internal mitochondrial membrane. Each of the mitochondrial membranes has a thickness, which varies between 50 to 70 A⁰ (figure. 19.7). The internal mitohondrial membrane borders a region full of a substance called the mitochondrial matrix, and gives rise to crests, tubules and septa, which add considerably to the internal surface. The structure of a mitochondrion depends on the state of cellular differentiation. Thus the internal surface is very developed in the cells that are strongly differentiated and physiologically very active. mitochondria carry enzymes, which are responsible for the processes of cellular oxidation, and play the role of an energy center. Mitochondria contain its own DNA and apparatus of protein synthesis including ribosome.

Figure 19.7a Mitochondria:

1, 2 - external and internal membranes, 3 - cristae, 4 - DNA, 5 - ribosomes, 6 - enzymes.

Figure 19.7b Mitochondria

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