Biodiversity and Cladistics Lecture Review

Flashcards covering the classification of organisms, cladistics, molecular homology, and the three domains of life as outlined in the lecture notes.

Taxon (plural: taxa)

A level within the hierarchical system used by biologists to classify all living organisms.

Taxonomic Ranks

The hierarchical sequence of classification which includes Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Chordata

The Phylum characterized by the presence of a backbone.

Hominid

The Family classification within the order Primate characterized by having no tail.

Homo

The Genus classification for humans characterized by being bipedal.

Phylogenetics

The determination of evolutionary relationships between species.

Cladistics

The specific organization of species into classification systems based on evolutionary relationships.

Molecular sequences

Base sequences of genes or amino acid sequences of proteins used as the most objective evidence for grouping organisms by common ancestry.

Codon degeneracy

The reason why amino acid sequences have the slowest rate of mutation compared to DNA sequences.

Clade

A group of related organisms that has evolved from a common ancestor, consisting of an ancestral organism and all its evolutionary descendants.

Cladogram

A branching tree diagram used to show evolutionary relationships between multiple species.

Root

The starting point on a cladogram from which all branches extend, representing the most recent common ancestor of all organisms in the diagram.

Outgroup

A species on a cladogram that is most distantly related to all others, used as a reference point for comparing the ingroup.

Node

A branch point on a cladogram representing a point of evolutionary divergence or a speciation event.

Phylogram

A type of tree diagram where branch lengths represent evolutionary time scales, often based on molecular clocks.

Molecular clock

A concept used to calculate the period of time since divergence based on the linear trend of mutations accumulating in gene or protein sequences.

Mitochondrial DNA (mtDNA)

Genetic material used for molecular clocks due to its maternal inheritance, lack of recombination, high copy number, and higher mutation rate.

Reactive Oxygen Species (ROS)

The substances that cause mitochondrial DNA to mutate at a faster rate than nuclear DNA.

Scrophulariaceae

The traditional family name for figworts, which originally contained more than $5000$ species before being reclassified using chloroplast DNA.

Domains of Life

The three overarching groups of all organisms—Bacteria, Archaea, and Eukarya—classified based on rRNA sequence evidence.

70S Ribosomes

The type of ribosomes found in the domains Bacteria and Archaea.

80S Ribosomes

The type of ribosomes found in the domain Eukarya.

Peptidoglycan

A cell wall component present in the domain Bacteria but absent in Archaea and Eukarya.