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The Main Themes of Microbiology
Chapter 1
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The Scope of Microbiology
Section 1.1 The Scope of Microbiology
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Microbiology Specialized area of biology that deals with organisms too small to be seen with the naked eye Microorganisms or microbes Germs, viruses, or agents “Bugs”
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Major Groups of Microorganisms
Bacteria Algae Protozoa Helminths Fungi Viruses: non-cellular, parasitic, protein-coated genetic elements
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Study of Microbes is Easy AND Difficult
Reproduce rapidly, large populations can be grown in the laboratory Can’t be seen directly, must be analyzed through indirect methods in addition to using microscopes
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Aspects of Microbiological Study
Medical Microbiology Public health Microbiology and Epidemiology Immunology
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Aspects of Microbiological Study
Industrial Microbiology Agricultural Microbiology Environmental Microbiology
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Check Your Understanding
What types of organisms are considered microbes? Provide some examples of these organisms. What types of cells can viruses infect? List and describe three branches of microbiology. Identify professions that make use of microbiology.
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The Impact of Microbes on Earth: Small Organisms with a Giant Effect
Section 1.2 The Impact of Microbes on Earth: Small Organisms with a Giant Effect
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The Impact of Microbes on Earth
Microbes have shaped the development of the earth’s habitats and the evolution of other life forms for billions of years Single-celled organisms arose 3.5 billion years ago Bacteria, archaea, and eukaryotes arose from this ancestor
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Types of Cells Eukaryotes: true nucleus Prokaryotes: “pre” nucleus
Cells with a nucleus are classified as eukaryotes Prokaryotes: “pre” nucleus Bacteria and archaea do not have a nucleus and have been traditionally classified as prokaryotes This classification is no longer used because bacteria and archaea are so distinct genetically
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Bacteria are Ubiquitous
Can be found: Deep in the earth’s crust Polar ice caps Oceans Inside the bodies of plants and animals
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Photosynthesis Involved in the flow of energy and food through the earth’s ecosystems Photosynthetic microorganisms account for more than 70% of the earth’s photosynthesis Production of oxygen by oxygenic photosynthesis evolved later allowing a diversification of species
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Decomposition Breakdown of dead matter and wastes
Accomplished by bacteria and fungi
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Microbes Are Vital In Shaping Earth
Microbes are the main forces that drive the structure and content of soil, water, and atmosphere Gas production by microbes Microbes living within the earth’s crust Bacteria and fungi living in complex associations with plants
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Check Your Understanding
Describe the difference between a prokaryote and a eukaryote. Describe the role and impact of microbes on the earth. Describe the basic tenets of the Theory of Evolution. True/False: Microscopic organisms produce more oxygen than plants. True/False: More than 50% of the microbes on the planet live below the Earth’s crust.
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Section 1.3 Human Use of Microbes
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Importance of Microbes to Humans
Humans have been using microorganisms for thousands of years to improve life and even shape civilizations Yeast for production of bread, wine, and beer Other fungi used for cheese production Moldy bread used in Egypt to treat wounds
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Uses for Microbes Biotechnology Genetic Engineering
Manipulation of microorganisms to make products in an industrial setting Genetic Engineering Manipulates the genetics of microbes, plants, and animals for the purpose of creating new products and genetically modified organisms (GMOs)
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Uses for Microbes Recombinant DNA technology: Bioremediation:
Techniques that allow the transfer of genetic material from one organism to another and deliberately alter DNA Bioremediation: introduction of microbes into the environment to restore stability or to clean up toxic pollutants
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Check Your Understanding
Name three products produced by genetically modified organisms that benefit humans. Describe one method in which microbes are used for bioremediation.
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Infectious Diseases and the Human Condition
Section 1.4 Infectious Diseases and the Human Condition
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Pathogen Any agent (virus, bacterium, fungus, protozoan, or helminth) that causes disease Nearly 2,000 different microbes cause disease
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Combating Infectious Diseases
New (emerging) diseases as well as older (reemerging) diseases are increasing AIDS, hepatitis C and viral encephalitis Polio, leprosy, and parasitic worm diseases have largely been eradicated
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Knowledge of Diseases Is Improving
Certain diseases once considered noninfectious are now found to be caused by microbes Gastric ulcers caused by Helicobacter pylori Link between certain cancers and bacteria and viruses Cocksackie virus has been associated with diabetes The Borna agent has been linked to schizophrenia
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Clinical Work Against Disease Continues
During the Golden Age of Microbiology, “obvious” diseases were characterized and cures or preventions were devised Today, we are discovering the subtler side of microorganisms and the quiet, slow, destructive diseases they cause An increasing number of patients with weakened immune systems are subject to infections by common microbes not pathologic to healthy people Drug-resistant microbes also contribute to the increase in infectious disease
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Check Your Understanding
True/False: All microbes cause disease. Why is there a difference between the top 10 causes of death in the U.S. versus worldwide? Name three connections between diseases considered to be noninfectious and a microbe.
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General Characteristics of Microorganisms
Section 1.5 General Characteristics of Microorganisms
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General Categories of Microbes
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Bacteria and Archaea About 10x smaller than eukaryotic cells
Lack organelles: small, double-membrane-bound structures that perform specific functions All bacterial and archaeal cells are single-celled
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Helminthes Not true microorganisms, but are included in the study of infectious disease: They are transmitted similarly to bacterial diseases The human body responds to them in the same way as it responds to bacterial diseases Their identification requires use of microscopes to view larvae and mouth parts
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Five Types of Microbes
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