Systematic Biology and Classification

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Questions and Answers

What was the major contribution of Aristotle to the field of systematic biology?

Devising the system of Binomial Nomenclature

Introduction of the concept of Prokaryotes and Eukaryotes

Division of living organisms into five kingdoms

Division of the living world into two kingdoms, plants and animals (correct)

What was the significance of the microscope in the 19th century in the field of classification?

It helped in the classification of organisms into five kingdoms

It revealed the existence of single-celled organisms (correct)

It led to the discovery of viruses

It was used to study the environmental adaptations of organisms

What was the outcome of the division of the kingdom Protista in 1938?

The development of the Binomial Nomenclature system

The division of Protista into two kingdoms, Monera and Protista (correct)

The creation of a new kingdom, Eukarya

The classification of all organisms into two domains

What is the characteristic that distinguishes Prokaryotes from Eukaryotes?

The absence of cell organelles Signup and view all the answers

What is the current system of classification used in biology?

The three-domain system Signup and view all the answers

What is the hierarchy of classification levels, from most general to most specific?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Signup and view all the answers

Who is credited with devising the system of Binomial Nomenclature?

Carolus Linnaeus Signup and view all the answers

What is the purpose of the Binomial Nomenclature system?

To provide a universal naming system for organisms Signup and view all the answers

What is the basis for classifying bacteria in a hierarchic system?

Phenotypic characteristics Signup and view all the answers

What is the purpose of determining the GC content in DNA composition?

To estimate the mol% of guanine + cytosine Signup and view all the answers

What is the significance of the sequence analysis of the (16S/23S) rRNA or (16S/23S) rDNA?

It provides information on the evolutionary relationships between bacteria Signup and view all the answers

What is the term for the study of the classification, naming, and identification of organisms?

Taxonomy Signup and view all the answers

What is the basic unit of classification in the hierarchic system?

Species Signup and view all the answers

What is the suffix used to form the names of families in biological classification?

-aceae Signup and view all the answers

What is the term for the study of the naming of organisms?

Nomenclature Signup and view all the answers

What is the domain to which bacteria belong?

Bacteria Signup and view all the answers

What is the purpose of biochemical tests in identifying bacteria?

To define the nutritional and physiological interaction of bacteria with their environment Signup and view all the answers

What is the significance of highly conserved sequences in bacterial genetic material?

They are found in all bacteria and are highly conserved Signup and view all the answers

What is the function of differential staining in identifying bacteria?

To differentiate between bacteria based on their cell wall composition Signup and view all the answers

What is the purpose of the International Code for the Nomenclature of Bacteria?

To establish a universal system for naming bacterial species Signup and view all the answers

What is the significance of family names in bacterial nomenclature?

They always end in -aceae Signup and view all the answers

What is the purpose of dichotomous keys in identifying bacteria?

To identify bacteria based on their morphological characteristics Signup and view all the answers

What is the significance of the genus name in bacterial nomenclature?

It characterizes the genus of bacteria Signup and view all the answers

What is the purpose of the 'International Committee of Systematic Bacteriology'?

To approve taxonomic names of bacteria Signup and view all the answers

What is the primary goal of taxonomy?

To provide a universal system of identification for organisms Signup and view all the answers

What is the characteristic feature of the genus name 'Klebsiella'?

It is named after a person Signup and view all the answers

What is the primary method used to determine phylogenetic relationships among bacteria?

rRNA sequencing Signup and view all the answers

What is the characteristic feature of the domain Eukarya?

Multicellular, photoautotrophic organisms Signup and view all the answers

What is the purpose of phage typing?

To determine the susceptibility of a bacterial strain to certain phages Signup and view all the answers

What is the characteristic feature of the specific epithet 'pyogenes'?

It refers to the formation of pus Signup and view all the answers

What is the primary difference between classification and identification?

Classification is a broader concept, while identification is a more specific concept Signup and view all the answers

What is the goal of the project to identify all organisms by 2025?

To provide a universal system of identification for organisms Signup and view all the answers

Study Notes

Classification of Living Organisms

Systematic biology involves providing scientific names, descriptions, preserving collections, classification, identification, and studying evolutionary histories and environmental adaptations.

History of Classification

Aristotle (384-322 BC) divided the living world into two kingdoms: plants and animals.
The two-kingdom system persisted for over 2000 years.
By the 19th century, the microscope revealed tiny single-celled organisms, leading to the creation of a third kingdom, Protista.
Protista included bacteria, algae, and fungi.

Development of Classification Systems

In 1938, Protista was divided into two kingdoms: Monera (unicellular prokaryotic microorganisms, including bacteria) and Protista (eukaryotic microorganisms, including algae and fungi).
In the 1940s, biologists divided living organisms (except viruses) into two distinct groups: Prokaryotes (bacteria) and Eukaryotes (all other organisms).
Prokaryotes have cells that lack a nucleus and other cell organelles.
Eukaryotes consist of cells that contain nuclei and other organelles.

The Three-Domain System

The three-domain system is currently used, replacing the old five-kingdom system.
Domain Bacteria and Domain Archaea comprise the prokaryotes.
Domain Eukarya includes all eukaryotic organisms.

Classification Levels

There are eight levels of classification: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Binomial Nomenclature

Carolus Linnaeus devised the Binomial Nomenclature system for naming organisms.
The system uses two names: genus and species (e.g., Gray wolf - Canis lupus).
Canis lupus is native to North America and Eurasia.

Taxonomy

Includes classification and nomenclature
Based on phenotypic characteristics (morphological, physiological, and chemical)
The basic unit is the species
Similar species are classified in a single genus and related genera are placed in a single family

Classification

Bacteria are grouped in the domain Bacteria to separate them from Archaea and Eucarya
Classification is based on relationships best elucidated by knowledge of evolutionary facts
However, little is known about phylogenetic relationships, so classification is often based on similarities among phenotypic characteristics
Chemical characteristics are growing in importance, e.g., murein composition or presence of certain fatty acids in the cell wall
DNA and RNA structure are highly important in classification
DNA composition can be estimated by determining the proportions of bases (mol/l of guanine + cytosine, GC)
DNA-DNA hybrids provide information on the similarity of different bacteria and their degree of relationship
Sequence analysis of 16S/23S rRNA or rDNA is highly useful in determining phylogenetic relationships

Morphological Characteristics

Microscopic morphology: cell shape, size, arrangement, staining, capsule characteristics, spore morphology, and flagellar arrangement
Colonial morphology: colonial appearance, color, shape, texture, margin, and elevation

Biochemical Tests

Examples: fermentation/oxidation of carbohydrates, enzyme activities, metabolism of organic acids, lipids, proteins, and amino acids
pH or redox range of growth and tolerance of chemical agents
These tests collectively define nutritional and physiological interactions of the organism with its environment

Identifying Bacteria

Dichotomous keys used for morphological identification of organisms
Differential staining: Gram staining, acid-fast staining
Biochemical tests: determine presence of bacterial enzymes

Nomenclature

Rules are set out in the International Code for the Nomenclature of Bacteria
A species is designated with two Latinized names, the first of which characterizes the genus and the second the species
Family names always end in -aceae
Taxonomic names approved by the "International Committee of Systematic Bacteriology" are considered official

Hierarchy

Species
Genus
Family
Order
Class
Division
Phylum
Kingdom (1969)
Domain (1980s)

Phylogeny or Systematics

Shows evolutionary relationships and history among organisms
Some obtained from fossil record
Most bacteria use rRNA sequencing or other sequence information
A goal is to identify all organisms by 2025

The 5 Kingdoms

Based on nutrient procurement
Plantae: multicellular photoautotrophs
Animalia: ingestive
Fungi: absorptive
Protozoa: mostly single-celled
Prokaryotes: bacteria

Phage Typing

Determining a strain's susceptibility to certain phage or bacterial viruses

Genetics

DNA base composition: guanine + cytosine moles% (GC)
DNA fingerprinting: electrophoresis of restriction enzyme digests
rRNA sequencing
Polymerase Chain Reaction (PCR)
DNA Hybridization

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Description

Quiz about the field of systematic biology, including classification, naming, and identification of organisms. Explore the history of classification, from Aristotle to modern systems.