High Power Microscopes and Bacteria Energy Metabolism
Bacterial cells, like the cells of all living organisms, accomplish work and are seen with microscopy. For this they require a source of energy. Although the wide variety of compounds that serve as a source of energy for microorganisms is almost limitless, there is a remarkable plainness in the basic metabolic patterns utilized to transform this energy into a useful form. Many of these systems are fundamentally similar to those found in the higher forms of life, but superimposed on these basic mechanisms are examples of differentiation unique to the bacterial world.
Bacteria can be divided into two large groups on the basis of their carbon requirement, the autotrophic or lithotrophic bacteria and the heterotrophic or organotrophic organisms. They are only viewed or observed with the science of microscopy. The autotrophic bacteria can utilize carbon dioxide as the sole source of carbon and synthesize from it the carbon skeletons of all their organic metabolites. They require only water, inorganic salts, and carbon dioxide for growth. Their energy is derived either from light or from the oxidation of one or more inorganic materials. The photosynthetic autotrophs or photolithotrophs obtain energy for their synthetic activities by the utilization of radiant energy. These are anaerobic organisms containing a magnesium porphyrin pigment closely related to chlorophyll of green plants. Chemosynthetic autotrophs or chemolithotrophs obtain their energy from oxidation-reduction reactions using simple inorganic electron donors, such as hydrogen, hydrogen sulfide, sulfur, or ammonia. Their activities using a stereo microscope are better observed and studied.
The heterotrophic bacteria are unable to utilize carbon dioxide as the sole source of carbon but require that it be supplied in an organic form. Most of these organisms require complex organic molecules, such as glucose, as electron donors. For the heterotrophic bacteria, a portion of the organic compound that serves the organism as an energy source invariably is used for the synthesis of many or all of the organic compounds required by the organism. This group contains all of those bacteria pathogenic for man. The pathogeneses of men are determined with microscopy using various microscopes.
The systems in bacteria that transform chemical and radiant energy into a biologically useful form include respiration, fermentation, and photosynthesis. These transformations are greatly observed in microscopy. In respiration, molecular oxygen is the ultimate electron acceptor, while in fermentation the foodstuff molecule is usually broken down into two fragments, one of which is then oxidized by the other. In photosynthesis, light energy is converted into chemical energy. In all types of cells, however, and regardless of the mechanism used to extract useful energy, the reaction is accompanied by the development of adenosine troposphere or ATP. ATP is a regular intermediate of both energy-mobilizing and energy-requiring reactions, and its formation provides a mechanism by which the available energy may be channeled into the energy-requiring biosynthetic reactions of the cell. The study of energy metabolism is the study of ATP production.
The metabolic activity of bacteria is very high. This is manifested both in a very rapid rate of cell division and in a high rate of catabolism. Associated with these processes is a very noticeable evolution of heat, much greater than for other organisms. Since the heat produced during metabolism represents that fraction of the total free energy change that is unavailable to the organisms for the performance of work, bacteria in general are less efficient as converters of free energy than are organisms with a slower metabolic rate. The metabolisms of these bacteria are customarily observed and studied in microscopy using various microscopes such as light microscopes, stereo microscopes and other high-powered microscopes inclusive of electron microscopes.