In cell biology, a mitochondrion (pluralmitocho ndria)
is a membrane-enclosed organelle found in most eukaryotic cells. These
organelles range from 0.5–10 micrometers (μm) in diameter. Mitochondria
are sometimes described as "cellular power plants" because they generate
most of the cell's supply of adenosine triphosphate (ATP), used as a
source of chemical energy. In addition to supplying cellular energy,
mitochondria are involved in a range of other processes, such as
signaling, cellular differentiation, cell death, as well as the control
of the cell cycle and cell growth. Mitochondria have been implicated in
several human diseases, including mitochondrial disorders and cardiac
dysfunction, and may play a role in the aging process. The word
mitochondrion comes from the Greek μίτος or mitos, thread + χονδρίον orkhondrion, granule.
Several
characteristics make mitochondria unique. The number of mitochondria in
a cell varies widely by organism and tissue type. Many cells have only a
single mitochondrion, whereas others can contain several thousand
mitochondria. The organelle is composed of compartments that carry out
specialized functions. These compartments or regions include the outer
membrane, the intermembrane space, the inner membrane, and the cristae
and matrix. Mitochondrial proteins vary depending on the tissue and the
species. In humans, 615 distinct types of proteins have been identified
from cardiac mitochondria; whereas in Murinae (rats), 940 proteins
encoded by distinct genes have been reported. The mitochondrial proteome
is thought to be dynamically regulated. Although most of a cell's DNA
is contained in the cell nucleus, the mitochondrion has its own
independent genome. Further, its DNA shows substantial similarity to
bacterial genomes.
Quelle
Keine Kommentare:
Kommentar veröffentlichen