Microbiology Summary PDF

Chapter Summary 1 Microbes in Our Lives The Microbiome Microorganisms, cellular and viral, can interact with both human and nonhuman hosts in beneficial, neutral, or detrimental ways. Microorganisms provide essential models that give us fundamental knowledge about life processes. 1. Living thing...

Chapter Summary 1 Microbes in Our Lives The Microbiome Microorganisms, cellular and viral, can interact with both human and nonhuman hosts in beneficial, neutral, or detrimental ways. Microorganisms provide essential models that give us fundamental knowledge about life processes. 1. Living things too small to be seen with the unaided eye are called microorganisms. 2. Microorganisms are important in maintaining Earth’s ecological balance. 3. Everyone has microorganisms in and on the body; these make up the normal microbiota or human microbiome. The normal microbiota are needed to maintain good health. 4. Some microorganisms are used to produce foods and chemicals. 5. Some microorganisms cause disease. Naming and Classifying Microorganisms While microscopic eukaryotes (e.g., fungi, protozoa, and algae) carry out some of the same processes as bacteria, many of the cellular properties are fundamentally different. Nomenclature 1. In a nomenclature system designed by Carolus Linnaeus (1735), each living organism is assigned two names. 2. The two names consist of a genus and a specific epithet, both of which are underlined or italicized. Types of Microorganisms 3. Bacteria are unicellular organisms. Because they have no nucleus, the cells are described as prokaryotic. 4. Most bacteria have a peptidoglycan cell wall; they divide by binary fission, and they may possess flagella. 5. Bacteria can use a wide range of chemical substances for their nutrition. 6. Archaea consist of prokaryotic cells; they lack peptidoglycan in their cell walls. 7. Archaea include methanogens, extreme halophiles, and extreme thermophiles. 8. Fungi (mushrooms, molds, and yeasts) have eukaryotic cells (cells with a true nucleus). Most fungi are multicellular. 9. Fungi obtain nutrients by absorbing organic material from their environment. 10. Protozoa are unicellular eukaryotes. 11. Protozoa obtain nourishment by absorption or ingestion through specialized structures. 12. Algae are unicellular or multicellular eukaryotes that obtain nourishment by photosyn- thesis.  13. Algae produce oxygen and carbohydrates that are used by other organisms. 14. Viruses are noncellular entities that are parasites of cells. 15. Viruses consist of a nucleic acid core (DNA or RNA) surrounded by a protein coat. An envelope may surround the coat. 16. The principal groups of multicellular animal parasites are flatworms and roundworms, collectively called helminths. 17. The microscopic stages in the life cycle of helminths are identified by traditional microbiological procedures. Classification of Microorganisms 18. All organisms are classified into one of three domains: Bacteria, Archaea, and Eukarya. Eukarya include protists, fungi, plants, and animals. A Brief History of Microbiology Ability to understand the relationship between science and society The First Observations 1. Hooke’s observations laid the groundwork for development of the cell theory, the concept that all living things are composed of cells. 2. Anton van Leeuwenhoek, using a simple microscope, was the first to observe microorganisms (1673). The Debate over Spontaneous Generation 3. Until the mid-1880s, many people believed in spontaneous generation, the idea that living organisms could arise from nonliving matter. 4. Francesco Redi demonstrated that maggots appear on decaying meat only when flies are able to lay eggs on the meat (1668). 5. John Needham claimed that microorganisms could arise spontaneously from heated nutrient broth (1745). 6. Lazzaro Spallanzani repeated Needham’s experiments and suggested that Needham’s results were due to microorganisms in the air entering his broth (1765). 7. Rudolf Virchow introduced the concept of biogenesis: living cells can arise only from preexisting cells (1858). 8. Louis Pasteur demonstrated that microorganisms are in the air everywhere and offered proof of biogenesis (1861). 9. Pasteur’s discoveries led to the development of aseptic techniques used in laboratory and medical procedures to prevent contamination by microorganisms. The First Golden Age of Microbiology 10. The science of microbiology advanced rapidly between 1857 and 1914. 11. Pasteur found that yeast ferment sugars to alcohol and that bacteria can oxidize the alcohol to acetic acid. 12. A heating process called pasteurization is used to kill bacteria in some alcoholic beverages and milk.  13. Agostino Bassi (1835) and Pasteur (1865) showed a causal relationship between microorganisms and disease. 14. Joseph Lister introduced the use of a disinfectant to clean surgical wounds in order to control infections in humans (1860s). 15. Robert Koch proved that microorganisms cause disease. He used a sequence of procedures, now called Koch’s postulates (1876), that are used today to prove that a particular microorganism causes a particular disease. 16. In 1798, Edward Jenner demonstrated that inoculation with cowpox material provides humans with immunity to smallpox. 17. About 1880, Pasteur discovered that avirulent bacteria could be used as a vaccine for fowl cholera; he coined the word vaccine. 18. Modern vaccines are prepared from living avirulent microorganisms or killed pathogens, from isolated components of pathogens, and by recombinant DNA techniques. The Second Golden Age of Microbiology 19. The Second Golden Age began with the discovery of penicillin’s effectiveness against infections. 20. Two types of chemotherapeutic agents are synthetic drugs (chemically prepared in the laboratory) and antibiotics (substances produced naturally by bacteria and fungi to inhibit the growth of other microorganisms). 21. Paul Ehrlich introduced an arsenic-containing chemical called salvarsan to treat syphilis (1910). 22. Alexander Fleming observed that the Penicillium fungus inhibited the growth of a bacterial culture. He named the active ingredient penicillin (1928). 23. Researchers are tackling the problem of drug-resistant microbes. 24. Bacteriology is the study of bacteria, mycology is the study of fungi, and parasitology is the study of parasitic protozoa and worms. 25. The study of AIDS and analysis of the action of interferons are among the current research interests in immunology. 26. New techniques in molecular biology and electron microscopy have provided tools for advancing our knowledge of virology. 27. The development of recombinant DNA technology has helped advance all areas of microbiology. The Third Golden Age of Microbiology 28. Microbiologists are using genomics, the study of all of an organism’s genes, to study microbiomes in different environments. Microbes and Human Welfare Cell genomes can be manipulated to alter cell function. Microbes are essential for life as we know it and the processes that support life (e.g., in biogeochemical cycles and plant and/or animal microflora). Microorganisms provide essential models that give us fundamental knowledge about life processes. Humans utilize and harness microorganisms and their products. 1. Microorganisms degrade dead plants and animals and recycle chemical elements to be used by living plants and animals. 2. Bacteria are used to decompose organic matter in sewage. 3. Bioremediation processes use bacteria to clean up toxic wastes. 4. Bacteria that cause diseases in insects are being used as biological controls of insect pests. Biological controls are specific for the pest and do not harm the environment. 5. Using microbes to make products such as foods and chemicals is called biotechnology. 6. Using recombinant DNA, bacteria can produce important substances such as proteins, vaccines, and enzymes. 7. In gene therapy, viruses are used to carry replacements for defective or missing genes into human cells. 8. Genetically modified bacteria are used in agriculture to protect plants from frost and insects and to improve the shelf life of produce. Microbes and Human Disease Microorganisms, cellular and viral, can interact with both human and nonhuman hosts in beneficial, neutral, or detrimental ways. 1. The disease-producing properties of a species of microbe and the host’s resistance are important factors in determining whether a person will contract a disease. 2. Bacterial communities that form slimy layers on surfaces are called biofilms. 3. An infectious disease is one in which pathogens invade a susceptible host. 4. An emerging infectious disease (EID) is a new or changing disease showing an increase in incidence in the recent past or a potential to increase in the near future. Contributions to the field of microbiology by the following individuals are noted in this chapter: Oswald Avery Dmitri Iwanowski Maclyn McCarty Agostino Bassi François Jacob César Milstein Françoise Barré- Edward Jenner Jacques Monod Sinoussi Robert Koch John Needham George Beadle Rebecca Lancefield Louis Pasteur Martinus Beijerinck Antoine Lavoisier Francesco Redi Francis Crick Joshua Lederberg Ignaz Semmelweis Paul Ehrlich Carolus Linnaeus Lazzaro Spallanzani Alexander Fleming Joseph Lister Wendell Stanley Robert Hooke Colin MacLeod Edward Tatum Youyou Tu James Watson Carl Woese Anton van Leeuwenhoek Chaim Weizmann Rudolf Virchow Sergei Winogradsky