Biology Taxonomy and Classification

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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?

The process of discovering and recording the traits of organisms Signup and view all the answers

Who was Carl von Linné?

A Swedish botanist who laid down basic rules for classification Signup and view all the answers

What is Whittaker's tree based on?

Structural similarities and differences in cellular organization and nutrition acquisition Signup and view all the answers

What did Carl R. Woese devise?

A Three-Domain System of Classification Signup and view all the answers

What is the International Code of Nomenclature of Bacteria (ICNB)?

It provides the accepted labels by which organisms are universally recognized Signup and view all the answers

What is the binomial system of nomenclature?

Every organism is assigned a genus and a species of Latin or Greek derivation Signup and view all the answers

What are Genotypic characteristics?

Characteristics related to an organism's genetic makeup Signup and view all the answers

What are Phenotypic characteristics?

Features based on observable characteristics beyond the genetic level Signup and view all the answers

The two alternating sugars are ______.

N-acetyl-D-glucosamine (NAG) and N-acetyl-D-muramic acid (NAM) Signup and view all the answers

Which of the following microorganisms have no cell wall?

All of the above Signup and view all the answers

What is the Bacterial Cell Wall also referred to as?

Peptidoglycan or murein layer Signup and view all the answers

What characterizes a Gram Positive Cell Wall?

A very thick protective peptidoglycan layer Signup and view all the answers

What characterizes a Gram Negative Cell Wall?

A thin peptidoglycan layer and an outer membrane Signup and view all the answers

What is the primary stain in Gram staining?

Crystal violet Signup and view all the answers

What is the function of iodine in Gram staining?

It serves as a mordant Signup and view all the answers

What role does alcohol play in Gram staining?

It is used for decolorization Signup and view all the answers

What is Safranin red used for in Gram staining?

Counterstaining Signup and view all the answers

Which of the following bacteria exhibit natural gram variability?

Both A and B Signup and view all the answers

Which type of bacteria are all COCCI except?

All are Gram Positive Signup and view all the answers

Which of the following BACILLI are Gram Negative?

Clostridium Signup and view all the answers

Why do Mycoplasma & Ureaplasma usually show a gram-negative reaction?

They do not have a cell wall Signup and view all the answers

Why is it difficult to gram stain Mycobacterium and Nocardia?

Because 60% of the cell wall is made of hydrophobic lipids Signup and view all the answers

What characterizes an Acid-Fast Organism?

It contains a waxy layer of glycolipids and fatty acids Signup and view all the answers

What is the purpose of Acid-Fast Staining?

Specifically designed for bacteria with long-chain fatty acids in their cell walls Signup and view all the answers

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.
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.