EXAM 2: Taxonomy Flashcards
Taxonomy
the science of biological classification
Nomenclature
the choosing of names for things
Phylogeny
the evolutionary development/history of a taxonomic grouping of organisms
Oligonucleotide
short single-stranded DNA or RNA molecules
Species
collection of organisms that share the same sequences in their core housekeeping genes
Strain
a genetic variant descended from a single, pure, microbial culture
Biovars
a genetic variant that differs biochemically and physiologically
Core housekeeping genes
genes that are essential for life (organism can’t survive without it)
Taxon
is a unit of any rank (i.e. kingdom, phylum, class, order, family, genus, species) designating an organism or a group of organisms
Morphovars
a genetic variant that differs morphologically
Serovars
a genetic variant that differs in antigenic properties
Clade
a group consisting of an organism and its descendants
Parsimony
adoption of the simplest assumption in the formulation of a theory or in the interpretation of data
Explain the binomial nomenclature and how to properly identify organisms in this format
- Developed by Carolus Linnaeus
- Can be abbreviated after 1st use (H. sapiens)
- Each organism has 2 names
Genus name - Italicized and capitalized (Homo)
Species epithet/name - Italicized, not capitalized (sapiens)
List taxon categories used in the classification of organisms. What is a strain?
Life, Domain, KPCOFGS
- Species are collections of strains that share stable properties and differs significantly from other strains
Describe the 3 domains and the 6 kingdoms of organisms. Explain the key differences between organisms in each group.
3 Domains:
- bacteria, eukarya, archaea
6 Kingdoms:
- Eubacteria, Archaeabacteria, Protist, Fungi, Plantae, Animalia
Main differences:
- Bacteria have peptidoglycan in cell wall
- Archaea have NO peptidoglycan in cell wall
- Eukarya are multicellular
Describe traditional and modern methods used to classify microorganisms
Taxonomy consists of three separate by interrelated principles:
1. Classification → arrangement of organisms into groups (taxa/taxon)
2. Nomenclature → assignment of names to taxa
3. Identification → determination of taxon to which an organism belongs
Older method (Phenetic Classification)
Newer method (Phylogenetic Classification)
- uses SSU rRNAs
Phylogenetic trees
- Show inferred evolutionary relationships in the form of multiple branching lineages connected by nodes
- Nodes represent divergence event
- Length of branch represents the number of molecular changes between two nodes
SSU rRNA?
- Small subunit rRNAs (16S for prokaryotes)
- Highly conserved (least changes) so it is good for determining ancestors → genes encoding SSU rRNAs are the most frequently used sequence in phylogenetics
- 70% cutoff value for species definition (sequence homology)
