Back in the 1840s, the presence of granule-like structures within muscle cells and other cell types were being recognized by several scientists. (Ernster and Schatz 1981) In 1890, Richard Altmann, who was a cytologist, used a dye technique to detect the granules and termed them as “bioblasts.” He speculated that they were the basic units of cellular activity. (Ernster and Schatz 1981)
It was in 1898 when Carl Benda gave these bioblasts a new the Greek name “mitochondria” meaning thread granules. Discovery of the mitochondrion however, cannot be limited to just a few people. Over decades of time, many contributions have been made in relation to the properties and functions of the ...view middle of the document...
It is composed mainly of lipids and contains a mixture of enzymes. (Karp 2008) It also contains several transport proteins called porins. (Alberts et al 2008) These proteins consist of a barrel of β sheets and form large aqueous channels across the lipid bilayer which allows molecules to penetrate and undergo diffusion. (Alberts et al 2008) The porins of the outer membrane are able to undergo reversible closure as a response to cell conditions. (Karp 2008) When the porin channels are open the outer membrane is very permeable to ATP, NAD, and coenzyme A. (Karp 2008) Most molecules, depending on size, are able to pass through the outer membrane easily.
The inner membrane of the mitochondria is impermeable and highly specialized. (Karp 2008) In order for molecules or ions to gain access to the matrix of the mitochondria, special membrane transporters are required. It contains several different polypeptides, lipids, and phospholipids, including cardiolipin. (Karp 2008) The inner membrane has evolved from bacterial plasma membranes (Hood and Joseph 2204) and contains a series of double-layered sheets called cristae which meet with the inner membrane at the boundary of the organelle. These cristae project into the matrix and contain a large amount of the membrane surface. (Karp 2008)
Cristae consume one third of the liver cell and are said to be three times greater in the mitochondria of the cardiac muscle due to a larger demand for ATP in the heart cells. (Perkins et al 2009) Up until recently, cristae were believed to consist of invaginations of the inner membrane but it is now agreed that cristae and the inner membrane are functionally distinct even though they are linked to one another by narrow connections. (Karp 2008)
These two membranes of the mitochondria divide the organelle into two aqueous compartments. The first compartment is found within the interior of the mitochondria and is called the matrix. This and the inner membrane are the two parts of the mitochondria that do most of the work. (Karp 2008) The matrix contains several different enzymes, ribosomes, tRNAs, and DNA molecules. The other aqueous compartment formed by the membranes of the mitochondria is called the intermembrane space. This is the region between the inner and outer membranes. This space plays a primary role in oxidative phosphorylation. (Alberts et al 2008)
Studies that have been done on mitochondrial assembly along with protein import are important because if the appropriate combinations of gene products are not incorporated properly then it can lead to reduction of ATP synthesis and enhanced reactive oxygen species production which can lead to mitochondrial disease and cell death. (Hood and Joseph 2004)
Mitochondria also carry their own set of DNA. (Shock et al 2010) Mitochondrial DNA performs aerobic respiration in the cell and contains 5-methylcytosine at cpG dinucleotides in the nuclear genome. (Shock et al 2011) Mitochondrial DNA is solely inherited from...