What is taxonomy?
The science of classifying organisms
Two advantages of taxonomy?
Provides universal names for organisms and provides a reference for identifying organisms
Who is the 'father of taxonomy'?
What two major ideas did Carl Linnaeus come up with?
Scientific nomenclature and natural classification
What is scientific nomenclature?
The naming of organisms, 1st part is the genus and the second part is the species name
What is phylogeny?
The study of the evolutionary history of organisms
What is hierarchy?
A hierarchy is an organizational structure in which items are ranked according to levels of importance.
What is a taxon?
A group of one or more populations of an organism or organisms seen by taxonomists to form a unit.
The hierarchy of taxa reflects...
What is natural classification?
The theory of grouping species according to shared physical traits
What did Linnaeus propose as the Kingdoms?
Animalia, Vegetabilia and Minerals
What was the main downfall of natural classification proposed by Linnaeus?
Bacteria and archaea not considered by Linnaeus
Where did Nageli propose that bacteria should be placed?
In the plant kingdom - led to the term microflora
Who introduced the Protista kingdom?
Haeckel - grouped bacteria, protozoa, fungi and algae in to protista
Chatton came up with two kingdoms, prokaryota and eukaryota in 1937, why?
He used electron microscopy and distinguished between nucleated and non-nucleated cells
Before Carl Woese, what was used to classify bacteria?
Physical traits such as shape, number of cells, gram staining, growth temperature range, etc.
What did Carl Woese propose?
Five kingdoms, Bacteira, Archaebacteria, Protista, Fungi, Plantae and Animalia originally. Then elevated Domains above kingdoms
Who came up with the three domains and what are they?
Carl Woese - Eukaryotes, Archaea and Bacteria
What does Woese's classification emphasise?
The difference between bacteria and archaea
How did Woese come to separate bacteria and archaea?
Based on the observation that ribosomes are not the same in all cells
What did Woese do differently in classification?
He based the split on genetic rather than morphological traits
What did Woese analyse?
Small subunit ribosomal RNA from various organisms 16S for prokaryotes and 18S for eukaryotes
What does SSU rRNA stand for?
Small subunit ribosomal RNA
What does SSU rRNA encode?
Encode for RNA molecules used in translation of nucleic acid
SSU rRNA can be used because it is present in...
What is special about SSU rRNA?
Allows you to compare all living organisms with each other
Why is SSU rRNA essential for life?
If you lose the ability to synthesise proteins, the organism dies
Explain what the yellow region in the diagram shows
Highlighted in yellow are the sequences that are conserved throughout history - no mutations in these regions, so yellow regions must have to do with the function of SSU rRNA
Explain what the blue regions show
Differences in the SSU rRNA code, direct comparisons can be made between different organisms.
How does SSU rRNA serve as a molecular clock?
Measures the evolutionary relatedness of sequences
The more genetic differences between two sequences...
The less related they are
Why do sequences for housekeeping genes make good molecular clocks?
Found in all/most organisms and they are under functional pressure to aquire few mutations
What is the function of the diagram?
Provide quantitative data to construct a phylogenetic tree
What do phylogenetic trees show?
Phylogenetic trees show evolutionary relationships among different biological species that are believed to have a common ancestor
Woese's work lead to eight taxonomic rankings, they are...
Domain, kingdom, phylum, class, order, family, genus, species (King Philip came over for great spaghetti)
Two problems with single gene analysis (e.g. SSU rRNA)?
1. Lack of divergence between two very closely related sequences can limit effectiveness at distinguishing two organisms.
2. Fails to account for lateral gene transfer
How to overcome the two issues bought about by single gene analysis?
Multi-gene or entire genome comparisons could be made
Medical importance of phylogenetics?
Pathogenic bacteria isolated from the patient. Compare characteristics to traits from previously classified bacteria. Guides treatment.