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Questions and Answers
Under what condition can the names of genus and species be changed?
What is the purpose of the term 'Candidatus' in bacterial nomenclature?
Which identification method uses specific DNA sequences for detection?
What does it indicate if two bacterial species have a 16S sequence similarity of 98.7% or more?
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What is the main focus of genome-based bacterial taxonomy?
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Which category in the taxonomic hierarchy is defined as a group of individuals that share a high degree of similarity in various independent characteristics?
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What suffix is associated with the taxonomic category of 'Family'?
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Which type of metabolism do quimiotrofia organisms utilize?
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Which of the following describes an organism that requires high concentrations of salt for growth?
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What characterizes prokaryotic cells?
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Who was the first to observe live microorganisms?
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Which scientist is credited with the germ theory of disease?
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What significant medical advancement did Semmelweis contribute to the field of microbiology?
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Which of the following individuals is associated with the discovery of the first vaccine?
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Which technique did Lister develop to improve surgical outcomes?
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What discovery is credited to Watson and Crick in 1953?
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Which bacterium was identified by Neisser in 1876?
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What was the primary focus of the research conducted by Delbrück and Luria in 1943?
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What is the primary function of the ribosomes in prokaryotic cells?
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Which structure in prokaryotic cells helps maintain a constant internal state?
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What is the role of the periplasmic space in prokaryotic cells?
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Which of the following structures provides prokaryotic cells with a rigid shape?
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What is the primary function of fimbrias in prokaryotic cells?
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What best defines the term 'virulence' in relation to microorganisms?
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Which of the following statements about the miasma theory is accurate?
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Which ancient physician is noted for the concept that health depends on the balance of humors?
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What is the primary assertion of Koch's first postulate regarding infectious diseases?
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Which theory asserts that disease is a result of an imbalance in elemental forces like earth, water, and fire?
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Which scientist is credited with the identification of the relationship between microorganisms and disease, specifically with anthrax?
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What does the term 'contagium' refer to in the context of disease transmission?
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How did the understanding of disease evolve from the theory of teúrgica to the germ theory?
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Study Notes
Golden Age of Microbiology
- Scientists from 1665 - 1997 significantly advanced the understanding of microbiology, leading to the development of vaccines, aseptic surgeries, and the discovery of the causes of numerous diseases
- The period saw the first observations of cells and live microorganisms, disproving spontaneous generation, and pioneering the germ theory of disease
- Key figures include Robert Koch, Louis Pasteur, and Alexander Fleming
- Early theories of disease included the miasmatic theory, which attributed disease to miasmas (bad air), and the theory of contagium, which proposed disease transmission via inanimate objects or living persons.
- The germ theory of disease emerged in the 19th century and revolutionized the understanding of disease causation, attributing it to microorganisms.
- Koch established the principles of germ theory and developed the postulates for identifying specific microorganisms as causes of specific diseases, including tuberculosis, cholera, and anthrax.
Naming in bacteria
- The naming of bacteria follows specific rules outlined in the International Journal of Systematic and Evolutionary Microbiology
- Species names can be changed if a species is transferred to a different genus, if the reference strain belongs to a different genus, or if a microbe is included in two or more genera.
Candidatus Species
- When a species is real and scientifically important but does not meet the requirements of the Prokaryotic Code, it is designated as "Candidatus" to acknowledge its tentative naming.
Pattern-Based Identification Systems
- Microscopes are used to examine bacteria, their morphology is significant in their identification
- Biochemical profiles, PCR, gene sequencing, immunological tests, MALDI-TOF, and chemical profiles are used to identify distinct patterns that characterize specific bacteria, enabling their classification based on their unique properties.
Genome-Based Bacterial Taxonomy
- Genome analysis plays a crucial role in bacterial taxonomy, providing a comprehensive understanding of a bacterium's characteristics
- Comparison of full-length 16S rRNA gene sequences and ANI (Average Nucleotide Identity)- measures genome-wide similarity and divergence.
Bacterial Classification
- Kingdom- Domain
- Phylum
- Class
- Order
- Family
- Genus
- Species
Suffixes for Bacterial Classification
- -la for Class
- -ales for Order
- -aceae for Family
Species
- Species is the most fundamental taxonomic category, representing a distinct group of organisms with a high degree of similarity in various characteristics, analyzed through standardized methods, and often defined by genome coherence.
Energy Sources for Prokaryotes
- Prokaryotes can utilize different energy sources for survival
- Chemotrophy: Obtaining energy from chemical compounds
- Chemorganotrophy: Utilizing organic compounds as energy sources
- Chemolithotrophy: Using inorganic compounds as energy sources
- Phototrophy: Utilizing light energy
- Phototrophs: Organisms that capture light energy for their metabolism
- ATP, Adenosine Triphosphate, is the primary energy currency for most cellular processes
Oxygen Utilization
- Prokaryotes exhibit various oxygen requirements
- Obligate Aerobes: Require oxygen for growth
- Obligate Anaerobes: Cannot grow in the presence of oxygen
- Aerotolerant Anaerobes: Tolerate oxygen but do not require it for growth
- Facultative Anaerobes: Can grow with or without oxygen
- Microaerophiles: Require low oxygen concentrations
Carbon Requirements
- Carbon is a crucial nutrient for all life forms
- Heterotrophs: Obtain carbon from organic molecules
- Autotrophs: Utilize carbon dioxide (CO2) as their primary carbon source
Environmental Tolerance
- Prokaryotes exhibit diverse abilities to survive in extreme environments
- Alkaliphiles: Thrive in alkaline conditions (pH 7-25°C)
- Psychrophiles: Grow in cold environments (below 25°C)
- Hyperthermophiles: Adapt to extremely hot environments
- Acidophiles: Live in acidic conditions
- Halophiles: Require high salt concentrations for survival
- Barophiles: Thrive at high pressures
Archaea
- Archaea are a domain of organisms with unique characteristics, often found in extreme environments
- Most Archaea are chemotrophs, particularly chemolithotrophs, deriving energy from inorganic compounds
- Halobacterium is an exception, using light energy with photosensitive pigments
- Methanogens, a group of Archaea, are strict anaerobes that produce methane
- Halophiles require high concentrations of salt for survival
- Some Archaea, termed thermoacidophiles, lack a cell wall and thrive in extreme heat and acidity.
Prokaryotic Cells
- Prokaryotic cells lack a nucleus and have their genetic material (DNA) contained within a nucleoid region in the cytoplasm
- Distinct from eukaryotic cells that have a membrane-bound nucleus containing their DNA.
Prokaryotic Morphology
- Prokaryotes exhibit diverse shapes
- Cocci: Spherical
- Bacilli: Rod-shaped
- Spirilla: Spiral-shaped
- Spirochetes: Long, helical bacteria
- Filamentous bacteria: Filamentous structures
Prokaryotic Cell Structures and Functions
- Prokaryotic cells possess essential structures with specific functions
- Plasma membrane: Serves as the cell's outer boundary, controls the passage of nutrients and waste, and hosts key metabolic processes
- Gas vacuoles: Allow cells to float in aquatic environments
- Ribosomes: Sites of protein synthesis
- Inclusion bodies: Store carbon, phosphates, and other substances
- Nucleoid: Contains the DNA
- Periplasmic space: Holds enzymes and binding proteins for nutrient capture and transport
- Cell wall: Provides structural support and protects against osmotic lysis
- Capsule and slime layer: Enhance resistance to phagocytosis (engulfment by immune cells) and aid in attachment to surfaces
- Pili: Facilitate attachment to surfaces and conjugation (transfer of genetic material)
- Flagella: Enable movement
- Endospores: Dormant structures that allow bacteria to survive adverse conditions.
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Description
Test your knowledge on the Golden Age of Microbiology, covering pivotal scientists and discoveries from 1665 to 1997. Explore the development of germ theory, vaccine advancements, and the principles set by key figures like Robert Koch and Louis Pasteur. See how these breakthroughs have shaped modern medicine and our understanding of diseases.
