Microbiology: An Introduction - Chapter 1 Study Guide
Section 1: Microbes in Our Lives
Learning Objectives
1-1: List several ways in which microbes affect our lives.
1-2: Define microbiome, normal microbiota, and transient microbiota.
Overview
Microorganisms are organisms that are too small to be seen with the unaided eye.
Types of microbes include:
Bacteria
Fungi
Protozoa
Microscopic algae
Viruses
Key Functions of Microorganisms
Some microorganisms are pathogenic (disease-producing).
They decompose organic waste.
Microbes generate oxygen by photosynthesis.
They produce chemical products such as ethanol, acetone, and vitamins.
Microbes are used to produce fermented foods such as vinegar, cheese, and bread.
They synthesize products used in manufacturing and disease treatment (e.g., insulin).
Knowledge of microorganisms allows:
Prevention of food spoilage
Prevention of disease
Understanding causes and transmission of disease to prevent epidemics
Section 2: The Microbiome
Microbiome Overview
An adult human is composed of approximately 30 trillion body cells and harbors another 40 trillion bacterial cells.
The microbiome is defined as a group of microbes that live stably on/in the human body.
Functions of the microbiome include:
Helping to maintain good health
Preventing the growth of pathogenic microbes
Assisting the immune system in recognizing threats
Normal and Transient Microbiota
Normal microbiota: the collection of microorganisms on or in a healthy human being.
Begins to be acquired as newborns.
Can colonize the body indefinitely or transiently.
Colonization is possible only at body sites that provide nutrients and a supportive environment for microbial growth.
Research Initiatives
The Human Microbiome Project (HMPC): Initiated in 2007, aimed at determining the normal microbiota composition of various body areas and its relationship to human diseases.
The National Microbiome Initiative (NMI): Started in 2016, focuses on exploring the role of microbes in different ecosystems.
Section 3: Naming and Classifying Microorganisms
Learning Objectives
1-3: Recognize the system of scientific nomenclature.
1-4: Differentiate the major characteristics of microorganism groups.
1-5: List the three domains.
Scientific Nomenclature
Developed by Carolus Linnaeus in 1735.
Each organism is given two names: a genus name and a specific epithet (species name).
Scientific names are:
Italicized or underlined
The genus name is capitalized, and the specific epithet is lowercase
Used worldwide and can be descriptive or honor a scientist
Examples include:
Escherichia coli: honors Theodor Escherich and describes its habitat (the colon).
Staphylococcus aureus: describes its clustered spherical shape (staphylo- coccus) and golden color (aureus).
Classification of Microorganisms
Microorganisms are classified into the following categories:
Bacteria
Archaea
Fungi
Protozoa
Algae
Viruses
Multicellular animal parasites (e.g., helminths)
Domain Classification
Developed by Carl Woese in 1978, the three domains based on cellular organization are:
Bacteria
Archaea
Eukarya (includes protists, fungi, plants, and animals)
Section 4: A Brief History of Microbiology
Learning Objectives
1-6: Explain the importance of observations made by Hooke and van Leeuwenhoek.
1-7: Compare spontaneous generation and biogenesis.
1-8: Identify contributions to microbiology made by Needham, Spallanzani, Virchow, and Pasteur.
Key Historical Observations
1665: Robert Hooke noted that living things are composed of "little boxes," or cells, marking the beginning of the cell theory: all living things are composed of cells.
Anton van Leeuwenhoek (1623–1673) was the first to observe microbes, which he called "animalcules."
The Spontaneous Generation Debate
Spontaneous generation: Hypothesis that life arises from nonliving matter.
Biogenesis: Hypothesis that living cells arise only from preexisting living cells.
Important Experiments
Francesco Redi (1668) filled jars with decaying meat, demonstrating that maggots appeared in open jars but not in sealed ones.
John Needham (1745) put boiled nutrient broth in covered flasks; microbial growth occurred, supporting spontaneous generation.
Lazzaro Spallanzani (1765) boiled nutrient solutions in sealed flasks; no microbial growth observed, disputing spontaneous generation.
The Theory of Biogenesis
Rudolf Virchow (1858) stated that cells arise from preexisting cells.
Louis Pasteur (1861) demonstrated that microorganisms are present in air and disproved spontaneous generation through controlled experiments.
Section 5: The Golden Age of Microbiology
Key Contributions and Discoveries
The Golden Age of Microbiology (1857–1914) was marked by discoveries related to the relationship between microbes and disease, immunity, and antimicrobial drugs.
Pasteur showed that microbes are responsible for fermentation and food spoilage.
Fermentation: The microbial conversion of sugar to alcohol in the absence of air.
Pasteurization: The application of high heat for a short time to kill harmful bacteria in beverages.
The Germ Theory of Disease
Agostino Bassi (1835) showed that a silkworm disease was caused by a fungus.
Joseph Lister (1860s) used chemical antiseptics to prevent surgical infections inspired by Pasteur's findings.
Robert Koch (1876) discovered that a bacterium causes anthrax and formulated Koch's postulates to establish a causative relationship between a specific microbe and a specific disease.
Important Vaccination Discoveries
Edward Jenner (1796) inoculated a person with cowpox virus, granting immunity to smallpox.
Vaccination is derived from the Latin word "vaccinus," meaning cow.
Birth of Chemotherapy
Chemotherapy refers to the treatment of disease with chemicals, which include synthetic drugs and antibiotics.
The first synthetic drug, salvarsan, was developed by Paul Ehrlich to treat syphilis.
Discovery of Antibiotics
Alexander Fleming discovered penicillin in 1928, leading to its clinical use in the 1940s.
Section 6: Modern Developments in Microbiology
Microbiology Branches
Bacteriology: Study of bacteria.
Mycology: Study of fungi.
Parasitology: Study of protozoa and parasitic worms.
Immunology: Study of immune response and vaccination.
Virology: Study of viruses.
Key Molecular Biology Concepts
Microbial genetics: Study of heredity in microbes.
Molecular biology: Study of how DNA directs protein synthesis.
Genomics: Study of an organism's gene structure, which aids in classification of microorganisms.
Recombinant DNA technology has enabled significant advancements, including gene therapy and genetic modification of organisms.
Section 7: Microbes and Human Welfare
Beneficial Activities of Microorganisms
Microbial ecology studies the relationship between microorganisms and their environment, with bacteria crucial for recycling elements like carbon, oxygen, nitrogen, sulfur, and phosphorus.
Microbes are utilized in sewage treatment and bioremediation to detoxify pollutants.
Bacillus thuringiensis: A microbial insecticide that is harmless to humans and plants but deadly to pests.
Biotechnology harnesses microbes for food, chemical production, and genetic engineering.
Section 8: Microbes and Human Disease
Definitions
Resistance: The ability of the body to ward off disease.
Biofilm: A mass of microbes attached to solid surfaces, capable of causing infections and exhibiting antibiotic resistance.
Emerging infectious diseases (EIDs): New or increasing incidence diseases resulting from pathogen invasion.
Examples of Emerging Infectious Diseases
Zika Virus
Discovered in 1947; outbreaks in Micronesia and Brazil.
Transmission through mosquitoes and sexual contact; impacts on pregnancy.
Middle East Respiratory Syndrome (MERS)
Caused by MERS-CoV, 1,800 cases reported since 2014.
Developed penicillin resistance in the 1950s; vancomycin resistance reported 1990s.
Ebola Virus
Causes hemorrhagic fever, major outbreaks in Guinea in 2014.
Summary
Understanding the relationship between microorganisms and human health can help prevent and treat various diseases and improve public health practices.