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Ward's World+McGraw Hill Bacteriology_with_questions

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Bacteriology Article by J.C. Ensign, Department of Bacteriology, University of Wisconsin, Madison, Wisconsin. Key Concepts • Bacteriology, a specialized branch of microbiology, is the study of bacteria. • Bacteria display an incredible physiological diversity. • One of the most important events in the history of civiliza- tion was the discovery that bacteria cause disease. • Bacteria have no discrete, membrane-bound nucleus and no special intracellular membrane-bound organelles. Access to this content is available to Ward's World readers for free from McGraw Hill's AccessScience, an award-winning, digital STEM resource containing exclusive articles written by expert scientists and engineers; biographies of well-known scientific figures; science news, videos, and animations; and much, much more. Instructors can use AccessScience to guide students on their research project journeys, to help students understand scientific concepts, to support distance learning efforts, in flipped classroom approaches, and in countless other ways. Ward's World and AccessScience have partnered to offer educators a no-obligation, free trial subscription to AccessScience. Request your free trial today to discover how valuable AccessScience can be for you and your students! Get your free trial now. The study of bacteria. The science of bacteriology is a special- ized branch of microbiology concerned with bacteria (Fig. 1) Although bacteria are different in some important respects from all other kinds of cells, their basic processes of physiology and genetics are the same as in all forms of life. One unusual property of bacteria as a whole is their physiological diversity. Some bacteria live in the total absence of oxygen and convert complex carbohydrates to acids and alcohols (fermenta- tion), sulfate to hydrogen sulfide, nitrate to nitrogen gas, and hydrogen plus carbon dioxide to methane gas; other bacteria carry out photosynthesis by mechanisms nearly identical to plants; some bacteria can grow and multiply by using energy obtained from oxidation of sulfur, ammonia, hydrogen, or iron, while obtaining carbon for cell synthesis from carbon dioxide; and some can obtain their needed nitrogen from the gas in air. Humans and the planet Earth are profoundly affected by bacteria. There is solid evidence that oxygen first appeared in the air some 2 billion years ago as a result of the activity of bac- teria. Moreover, bacteria are critically important in the recycling of materials essential to plants and animals. The degradation of complex substances such as carbohydrates, proteins, and lipids, to carbon dioxide allows plants to grow. Conversion of ammonia to nitrate and of nitrogen gas to amino acids is also essential to plants. Great numbers of bacteria live on human skin surfaces as well as in the mouth and intestinal tract; most of these are benign or even beneficial. Some bacteria, given the opportunity, can cause severe diseases of humans, other animals, and plants. Relationship to other life forms Bacteria were considered to be primitive plants until approx- imately 1955, when improved technology of electron micros- copy made it possible to observe their intracellular structure. which was found to be much different and simpler than that of + ward ' s science Content • Relationship to other life forms • Bacteria and disease • Models for biochemistry and genetics • Biotechnology Fig. 1: Colorized transmission electron micrograph (TEM) of a Helicobacter pylori bacterium, which uses its flagella (hairlike strands) for locomotion. This bacterium commonly causes inflammation of the stomach lining and stomach ulcers. (Credit: Heather Davies/Science Source)

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