A3.2 Classification and Cladistics

classification

a system of organising knowledge on all living things based upon their characteristics and even DNA

hierarchy

A group organised into successive ranks or grades.

taxonomy

The scientific study of how living things are classified

taxon

A group of one or more populations of an organism or organisms seen by taxonomists to form a unit

Hierarchy of Taxonomy

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

clade

A group of species with a single common ancestor and a set of common traits or characteristics

cladistics

cladogram

a diagram that shows the relationships between a group of organisms in terms of evolution.

amino acid sequences

The arrangement of amino acids in a protein molecule.

See entire glossaryc

molecular clock

The technique that uses the mutation rate of biomolecules to deduce the time since two species shared a common ancestor.

calibration point

a period of time in which the precise moment at which two species diverged is known.

morphological

study of the form and structure of organisms and their specific structural features

the three domains

Bacteria, Archaea, Eukarya

root of cladogram

The initial ancestor common to all organisms within the cladogram

Node (on a cladogram)

a place where a branch splits off from the rest of the cladogram. represents a hypothetical ancestors

terminal branch of cladogram

represents an extant (existing) species

evolution

The gradual change in a species over time

common ancestor

An ancestral species from which later species evolved

archaea

Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan

eubacteria

domain of unicellular prokaryotes whose cell walls are made up of peptidoglycan

Eukarya

Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals

parsimony analysis

A technique for choosing among alternative phylogenetic trees by selecting the tree that requires the fewest character changes.