Lecture 10 Flashcards
taxonomy
the science of classifying organisms
taxonomy provides these two things
- universal names for organisms
- a reference for identifying organisms
_____ established the system of scientific nomenclature
Linneaus
each organisms has two names, which are…
- the genus
- specific epithet
How do you write a species name?
It is italicized, with the first letter of the genus is capitalized and the specific epithet is all lowercase
The accepted rules for naming species/taxa have been determined by who?
International Committee on Systematics of Prokaryotes
How do you establish a new microbial species?
It must be isolated and grown in a pure culture known as an isolate
what does the title Candidatus mean?
it is a candidate species
how does a candidate species become accepted as official?
upon publication in the International Journal of Systematic and Evolutionary Microbiology
Why are microbes hard to classify?
- they asexully reproduce
- horizontal gene transfer (can sometimes be between species)
molecular clock
temporal information contained in macromolecular sequence, which is based on the acquisition of new random mutations in DNA replication
What genes are the most consistent measures of evolutionary time?
those that encode components of the transcription and translation apparatus (ribosomal RNA and proteins, tRNA, and RNA polymerase)
what is the most widely used molecular clock gene?
small subunit rRNA (SSU rRNA)
- 16S rRNA in bacteria and 18S rRNA in eukaryotes
use of a molecular clock requires what?
the alignment of homologous sequences in divergent species or strains
phylogenetic trees estimate what?
the relative amounts of evolutionary divergences between sequences
practical identification is based on a combination of what two things?
phylogenetic and phenetic (phenotypic) traits
a common strategy of practical identification is what?
the dichotomous key
dichotomous key
a series of yes/no questions successively narrows down the possible categories of species
most traits of the dichotomous key are what kinds of traits?
phenotypic
taxonomic identification uses morphologic and metabolic properties like…(4)
- morphological characteristics
- biochemical tests
- growth substrates
- biochemical structure (differential staining)
rapid pathogen identification
it is a multicolor test that the results scored to give the most probable species
The purposes of taxonomy includes…
- classification
- identification
- nomenclature
- none of these
- all of these
none of these
the phylogenetic classification of the Domain Bacteria is based on what?
rRNA sequences
the binomial system of nomenclature assigns each organism a scientific name consisting of what two parts?
genus and species
