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PinkMonkey Online Study Guide-Biology
5.1 Ultrastructure and functions of Mitochondrion
Mitochondria are the special protoplasmic organelles
distributed in the cytoplasm of eukaryotic cells. Mitochondria contain
the biochemical machinery involved in cellular respiration which
take energy from breakdown of glucose and produce energy-rich ATP
molecule which fuel the biochemecal reactions in the rest of the
cell. Hence, mitochondria are described as the ‘power houses’
of cells.
Mitochondria were first observed by Altmann (1894).
Hogeboom (1948) discovered that mitochondria are the site of aerobic
respiration.
Ultrastructure (Figure 5.1) Mitochondria
are microscopic and granular or cylindrical,
Figure. 5.1 A mitochondrion in section
Ultrastructure of a mitochondrion
And are bound by two lipo-protein membranes called
outer and inner membranes. These are separated from each other by
the inter-membrane space.
The outer membrane is smooth, while the inner membrane
is highly folded. The folds are called cristae, and project
into the inner space of the mitochondrion and appear finger-shaped
in the section.
The internal space of the mitochondrion (enclosed
within the folded inner membrane) is filled with dense proteinaceous
material and is called the matrix. It contains small ribosomes
and mitochondrial DNA (DNA) invited in the replication of
mitochondria. The matrix also contains all the enzymes required
for the Kreb’s cycle reactions during the second phase of
aerobic respiration.
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