Fundamentals of Microbiology

1.3.1.2 Mitochondria

Mitochondria are approximately the same size as bacteria (2 – 3 µ m long and 1 µ m in dia). The number of mitochondria varies in cells from just 2 (in yeast cell) to up to 1000 (in a liver cell). The process of respiration and oxidative phosphorylation (the mechanism of ATP synthesis during respiration) are localized in membrane bound organelles (mitochondria) in eukaryotic organisms. The mitochondrial membranes lack sterols and are more permeable so that ATP synthesized within the mitochondrion can move into the cytoplasm. The inner mitochondrial membrane is highly folded to produce cristae. Cristae project into the mitochondrial lumen. The enzymes involved in ATP production and specific transport proteins which regulate the passage of metabolites into and out of the matrix are located within the inner membrane.

Enzymes of TCA cycle and β – oxidation are located in the matrix. Complexes of the enzyme ATP synthetase are present as small round particles attached to the cristae. These small sphere shaped particles are called F₁ particles and they synthesize ATP during cellular respiration. Mitochondria use its DNA and ribosomes to produce some of its own proteins. Mitochondria reproduce by binary fission.