Questions and Answers
What is Taxonomy?
The science of classifying living things
What is Nomenclature?
The assignment of scientific names to the various taxonomic categories and individual organisms
What is Classification?
The orderly arrangement of organisms into a hierarchy of taxa (categories)
What does Identification refer to in taxonomy?
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Who was Carl von Linné?
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What is Whittaker's tree based on?
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What did Carl R. Woese devise?
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What is the International Code of Nomenclature of Bacteria (ICNB)?
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What is the binomial system of nomenclature?
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What are Genotypic characteristics?
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What are Phenotypic characteristics?
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The two alternating sugars are ______.
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Which of the following microorganisms have no cell wall?
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What is the Bacterial Cell Wall also referred to as?
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What characterizes a Gram Positive Cell Wall?
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What characterizes a Gram Negative Cell Wall?
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What is the primary stain in Gram staining?
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What is the function of iodine in Gram staining?
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What role does alcohol play in Gram staining?
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What is Safranin red used for in Gram staining?
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Which of the following bacteria exhibit natural gram variability?
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Which type of bacteria are all COCCI except?
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Which of the following BACILLI are Gram Negative?
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Why do Mycoplasma & Ureaplasma usually show a gram-negative reaction?
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Why is it difficult to gram stain Mycobacterium and Nocardia?
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What characterizes an Acid-Fast Organism?
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What is the purpose of Acid-Fast Staining?
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Study Notes
Taxonomy and Bacterial Classification
- Taxonomy: The science of classifying living organisms, derived from the Greek words "taxes" (arrangement) and "nomos" (law).
- Nomenclature: Assignment of scientific names to various taxonomic categories and individual organisms.
- Classification: Organizes organisms into a hierarchy of taxa (categories) to facilitate study.
- Identification: Process of discovering and recording traits of organisms for recognition and classification based on genotypic and phenotypic characteristics.
Key Figures in Taxonomy
- Carl von Linné (Linnaeus): Established fundamental classification rules and taxonomic categories.
- Robert Whittaker: Developed Whittaker's tree; classification based on structural similarities, distinguishing between prokaryotic and eukaryotic organisms.
- Carl R. Woese: Introduced the Three-Domain System of Classification, including Archaea, Bacteria, and Eucarya.
Bacterial Naming and Structure
- International Code of Nomenclature of Bacteria (ICNB or Bacteriological Code): Provides accepted labels for universal recognition of organisms.
- Binomial System: Each organism is assigned a Latin or Greek-derived genus and species name.
- Genotypic Characteristics: Focus on an organism's genetic makeup, including genes and nucleic acids.
- Phenotypic Characteristics: Relate to observable features of organisms, requiring varying degrees of analysis for detection.
Structural Components of Bacteria
- N-acetyl-D-glucosamine (NAG) and N-acetyl-D-muramic acid (NAM): Two alternating sugars forming part of bacterial cell walls.
- Bacterial Cell Wall: Known as the peptidoglycan or murein layer; provides shape, strength, and protection against osmotic pressure and mechanical disruption.
Gram Staining and Cell Wall Types
- Gram Positive Cell Wall: Thick peptidoglycan layer, teichoic and lipoteichoic acids providing rigidity and attracting cations.
- Gram Negative Cell Wall: Thin peptidoglycan layer, periplasmic space, and an outer membrane composed of proteins, phospholipids, and lipopolysaccharides (LPS).
- Crystal Violet: Primary stain in Gram staining procedure.
- Iodine: Acts as a mordant to strengthen primary stain affinity.
- Alcohol: Used for decolorization in the Gram staining process.
- Safranin Red: Counterstain used in Gram staining to visualize Gram-negative cells.
Variability and Specific Bacteria
- Gram Variability: Example organisms include Mobiluncus spp. and Gardnerella vaginalis, displaying natural variability in Gram reactions.
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Exceptions in Gram Reaction:
- All cocci are Gram positive except for Neisseria and Branhamella/Moraxella, and Veilonella.
- All bacilli are Gram negative except for Mycobacterium, Bacillus, Clostridium, and several others.
- Mycoplasma & Ureaplasma: Have a gram-negative reaction due to the absence of a cell wall.
- Mycobacterium and Nocardia spp.: Have gram-positive structures but include significant hydrophobic lipids that affect staining permeability.
Acid-Fast Organisms and Staining Techniques
- Acid-Fast Organisms: Contain a waxy layer with more than 60% of their cell wall being lipid, mainly mycolic acid, contributing to their unique staining properties.
- Acid-Fast Staining: A specialized staining method designed for bacteria with high lipid content in their cell walls, facilitating their identification.
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Description
Flashcards covering taxonomy, nomenclature, and classification in biology. Learn the science of classifying living things and the orderly arrangement of organisms.