Biologic Principles Illustrated by Microbiology PDF

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Naresuan University Access Provided by: Jawetz, Melnick, & Adelberg's Medical Microbiology, 28e Chapter 1: The Science of Microbiology BIOLOGIC PRINCIPLES ILLUSTRATED BY MICROBIOLOGY Nowhere is biologic diversity demonstrated more dramatically than by microorganisms, cells, or viruses that are not directly visible to the unaided eye. In form and function, be it biochemical property or genetic mechanism, analysis of microorganisms takes us to the limits of biologic understanding. Thus, the need for originality—one test of the merit of a scientific hypothesis—can be fully met in microbiology. A useful hypothesis should provide a basis for generalization, and microbial diversity provides an arena in which this challenge is ever present. Prediction, the practical outgrowth of science, is a product created by a blend of technique and theory. Biochemistry, molecular biology, and genetics provide the tools required for analysis of microorganisms. Microbiology, in turn, extends the horizons of these scientific disciplines. A biologist might describe such an exchange as mutualism, that is, one that benefits all contributing parties. Lichens are an example of microbial mutualism. Lichens consist of a fungus and phototropic partner, either an alga (a eukaryote) or a cyanobacterium (a prokaryote) (Figure 1­1). The phototropic component is the primary producer, and the fungus provides the phototroph with an anchor and protection from the elements. In biology, mutualism is called symbiosis, a continuing association of different organisms. If the exchange operates primarily to the benefit of one party, the association is described as parasitism, a relationship in which a host provides the primary benefit to the parasite. Isolation and characterization of a parasite—such as a pathogenic bacterium or virus—often require effective mimicry in the laboratory of the growth environment provided by host cells. This demand sometimes represents a major challenge to investigators. FIGURE 1­1 Diagram of a lichen, consisting of cells of a phototroph, either an alga or a cyanobacterium, entwined within the hyphae of the fungal partner. (Reproduced with permission from Nester EW, Anderson DG, Roberts CE, et al: Microbiology: A Human Perspective, 6th ed. McGraw­Hill, 2009, p. 293. © McGraw­Hill Education.) The terms mutualism, symbiosis, and parasitism relate to the science of ecology, and the principles of environmental biology are implicit in microbiology. Microorganisms are the products of evolution, the biologic consequence of natural selection operating on a vast array of genetically Downloaded 2024­8­3 diverse organisms. 5:15 AtoYour It is useful keepIP iscomplexity the 110.170.245.47 of natural history in mind before generalizing about microorganisms, the most heterogeneous BIOLOGIC PRINCIPLES ILLUSTRATED subset of all living creatures. BY MICROBIOLOGY, Page 1 / 2 ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility A major biologic division separates the eukaryotes, organisms containing a membrane­bound nucleus from prokaryotes, organisms in which DNA is not physically separated from the cytoplasm. As described in this chapter and in Chapter 2, further major distinctions can be made between eukaryotes  Naresuan University Access Provided by: The terms mutualism, symbiosis, and parasitism relate to the science of ecology, and the principles of environmental biology are implicit in microbiology. Microorganisms are the products of evolution, the biologic consequence of natural selection operating on a vast array of genetically diverse organisms. It is useful to keep the complexity of natural history in mind before generalizing about microorganisms, the most heterogeneous subset of all living creatures. A major biologic division separates the eukaryotes, organisms containing a membrane­bound nucleus from prokaryotes, organisms in which DNA is not physically separated from the cytoplasm. As described in this chapter and in Chapter 2, further major distinctions can be made between eukaryotes and prokaryotes. Eukaryotes, for example, are distinguished by their relatively large size and by the presence of specialized membrane­bound organelles such as mitochondria. As described more fully later in this chapter, eukaryotic microorganisms—or, phylogenetically speaking, the Eukarya—are unified by their distinct cell structure and phylogenetic history. Among the groups of eukaryotic microorganisms are the algae, the protozoa, the fungi, and the slime molds. A class of microorganisms that share characteristics common to both prokaryotes and eukaryotes are the archaebacteria and are described in Chapter 3. Downloaded 2024­8­3 5:15 A Your IP is 110.170.245.47 BIOLOGIC PRINCIPLES ILLUSTRATED BY MICROBIOLOGY, Page 2 / 2 ©2024 McGraw Hill. All Rights Reserved. Terms of Use Privacy Policy Notice Accessibility