Mitochondria
...location for which respiration takes place. Mitochondria contain
enzymes that help convert food material into adenosine triphosphate (ATP), which
can be used directly by the cell as an energy source. Mitochondria tend to be
concentrated near cellular structures that require large inputs of energy, such
as the flagellum. The role of the mitochondria is very important in respiration.
In the presence of oxygen, pyruvate or fatty acids, can be further
oxidized in the mitochondria. Each mitochondrion is enclosed by two membranes
separated by an intermembrane space. The intermembrane space extends into the
folds of the inner membrane called cristae which dramatically increase the
surface area of the inner membrane. Cristae extend into a dense material called
the matrix, an area which contains RNA, DNA, proteins, ribosomes and range of
solutes. This is similar to the contents of the chloroplast stroma and like the
chloroplast, the mitochondrion is a semi-autonomous organelles containing the
machinery for the production of some of its own proteins. The main function of
the mitochondrion is the oxidation of the pyruvate derived from glycolysis and
related processes to produce the ATP required to perform cellular work.(Campbell
182-9)
Pyruvate, or fatty acids from the breakdown of triglycerides or
phospholipids, pass easily through pores in the outer mitochondrial membrane
made up of a channel protein called porin. The inner membrane is a more
significant barrier and specific transport proteins exist to carry pyruvate and
fatty acids into the matrix. Once inside the matrix, pyruvate and fatty acids
are converted to the two carbon compound acetyl coenzyme A (acetyl CoA). For
pyruvate this involves a decarboxylation step which removes one of the three
carbons of pyruvate as carbon dioxide. The energy released by the oxidation of
pyruvate at this stage is used to...
View Full Essay
