Classification Flashcards
How was classification previously done
By observations
How is classification done in the modern day
We use evidence from biological molecules to determine how closely related one species is to another, as opposed to observable features
Who was Carl Woese and what did he do
An American microbiologist who is most famous for defining the archaea as a new domain of life and this was adopted in 1990
What does the 3 domain system consist of
Archaea, Bacteria and Eukarya
What are the ranks of classification
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What is phylogeny
The study of the evolutionary relationship between organisms
What does phylogeny suggest
Any two species living today have had a common ancestor at some point in the past and at the time at which the two species started to evolve separately is shown as a branch point on the phylogenetic. The more recent the ancestor the more closely related.
What does the 3 domain system do
Adds a level of classification above the kingdoms. It recognises the fundamental divide between the two prokaryotic groups - archaea and bacteria
What did Carl Woese base his ideas on
A detailed study of the 16s ribosomal RNA gene, which is the sequence of bases that codes for 16s rRNA
What is 16s rRNA
A component of the 30s small subunit of a prokaryotic ribosome and is key to the production of proteins in all organisms
What was Woese’s method in his detailed study of the 16s Ribosomal RNA gene
He split the RNA into fragments that could be sorted and compared with other fragments from other organisms, where the more closely similar the patterns between species, the more closely they are related
What ways can genetic diversity within, or between species, be investigated
By comparing the base sequence of DNA or mRNA, comparing the amino acid sequence of the proteins encoded by DNA and mRNA and comparing 16s and 30s ribosomal structures
