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Animal Cell: Mitochondria
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In addition the optical and electron microscope, scientists are able to use a number of other techniques to probe the mysteries of the animal cell. Cells can be disassembled by chemical methods and their individual organelles and macromolecules isolated for study. The process of cell fractionation enables the scientist to prepare specific components, the mitochondria for example, in large quantities for investigations of their composition and functions. Using this approach, cell biologists have been able to assign various functions to specific locations within the cell. However, the era of fluorescent proteins has brought microscopy to the forefront of biology by enabling scientists to target living cells with highly localized probes for studies that don't interfere with the delicate balance of life processes.
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Some biologists believe that mitochondria and chloroplasts within eukaryotic animal and plant cells may have originated from ancient symbiotic bacteria that were once captured by other cells in the distant geologic past. This fascinating idea is called the "Endosymbiont Theory" (or "Endosymbiont Hypothesis" for those who are more skeptical). Chloroplasts and mitochondria have outer phospholipid bilayer membranes and circular DNA molecules like those of prokaryotic bacterial cells. In addition, the layers of thylakoid membranes in the grana of chloroplasts are remarkably similar to photosynthetic cells of cyanobacteria. Acquiring cells and genomes from other organisms is known as symbiogenesis. According to L. Margulis and D. Sagan (Acquiring Genomes: A Theory of the Origins of Species 2002), symbiogenesis is a major factor in the evolution of life of earth.
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Like all other animal and plant cells they contain mitochondria (singular mitochondrion). These are cell organelles. Their job is to obtain energy from glucose by tissue respiration. The energy produced by mitochondria is released into the cell in the form of ATP (Adenosine Tri-Phosphate).
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Mitochondria