TX: Taxonomy Lesson Overview

Wait... Taxes? In Biology?

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In this module, we will study the following topics:

Classification, Modern Classification, Kingdoms & Domains, Dichotomous Key

Module Key Terms

Taxonomy: The science of classification
Classification: a way of separating a large group of closely related organisms into smaller subgroups
Aristotle: Greek philosopher that developed a classification system based on where organisms live
Linnaeus: Swedish scientist who developed the system of classification still used today using the 7 taxa and binomial nomenclature
Taxon (plural: Taxa): a group of related organisms within a hierarchy; taxa are nested within each other so each level contains the organisms in the level below it; the 7 taxa are Kingdom, Phylum, Class, Order, Family, Genus, Species
Binomial Nomenclature: the two-name system for identifying organisms developed by Linnaeus
Common Names: terms that differ in different regions that can cause confusion when trying to identify organisms
Scientific Name: the two word (Genus and Species) name assigned to one organism; usually in Latin; the Genus is capitalized and the species is lowercase; it is usually written in italics or underlined
Dichotomous Key: a method for determining the identity of an organism by going through a series of choices that leads the user to the identity of the organism; dichotomous means “divided into two parts”
Domain: the broadest taxonomic rank of organisms; above Kingdoms; based on molecular data: the three domains are Archaea, Bacteria, Eukarya
Kingdom Archaebacteria: ancient forms of bacteria that live in harsh conditions
Kingdom Eubacteria: slightly more advanced bacteria found in three common shapes – cocci, spirilla, and bacilli; may be harmful or beneficial
Kingdom Protista: mostly unicellular organisms, organisms may be autotrophs or heterotrophs
Kingdom Fungi: mostly heterotrophic, multicellular organisms with cell walls made of chitin
Kingdom Plantae: multicellular, autotrophic plants with walls made of cellulose
Kingdom Animalia: multicellular, heterotrophic organisms with no cell wall
Phylogeny: the study of evolutionary relationships between organisms; uses similarities between DNA and RNA, similar amino acids, and physical characteristics
Cladogram: a diagram to illustrate a hypothesis about the evolutionary relationship between organisms based on derived characteristics
Clade: a group of organisms believed to have evolved from a common ancestor
Shared, Derived Characteristics: characteristics shared between a clade and its most recent common ancestor
DNA and RNA: nucleic acids found in eukaryotic organisms; controls growth, maintenance, and development; similar DNA and RNA are used to determine how closely related organisms are
Cladistic Analysis: scientists determine organisms' evolutionary history by looking at the gene sequence similarities in the DNA and RNA, as well as their physical characteristics
Molecular Clock: small segments of DNA are compared in 2 species to determine how dissimilar they are; since mutations in these segments occur at a constant rate, the dissimilarity indicates how long ago the two organisms shared a common ancestor