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What is the most recent taxonomic group to be added to the hierarchy classification system and, in order, what are the 7 taxonomic groups that follow it?
- 1. Domain
- 2. Kingdom, Phylum, Class, Order, Family, Genus, Species
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Why do scientists classify organisms?
- ☉ To identify species
- ☉ To predict characteristics - if a number of species in same group have similar characteristics, it is likely another species from that group will too.
- ☉ To find evolutionary links - similar characteristics within a group are likely to have evolved from a common ancestor
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How many Domains are there and what are they?
- 3 Domains
- ☆Archaea: 70s ribosomes, RNA polymerase has 8-10 proteins
- ☆Bacteria: 70s ribosomes, RNA polymerase has 5 proteins
- ☆Eukarya: 80s ribosomes, RNA polymerase contains 12 proteins
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What is Binomial Nomenclature?
- -Used worldwide so scientists can communicate effectively
- -First word indicates Genus - generic name (equivalent to surname)-Second word indicates species - specific name
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What are the 5 kingdoms?
- ProkaryotaeProtoctista FungiPlantaeAnimalia
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What are the general features of Prokaryotae?
- 'the prokaryotes'
- Unicellular
- No nucleus or membrane-bound organelles
- No visible feeding mechanism - nutrients either absorbed or produced internally e.g. by photosynthesis
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What are the general features of Protoctista?
- Eukaryotes
- (Mainly) unicellular
- Nucleus and other membrane bound organelles
- Some with chloroplasts
- Some are sessile, others move by cilia, flagella, amoeboid mechanisms
- Some autotrophic, some heterotrophic, some both - parasitic
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What are the general features of Fungi?
- Uni or multi cellular
- Nucleus & other membrane-bound organelles
- Cell wall of chitin
- No chloroplasts/chlorophyll
- No locomotion mechanisms
- Body or mycelium made of threads or hyphae (most)
- Saprophytic feeders - nutrients absorbed mainly from decaying material
- Most store food as glycogen
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What are the general features of Plantae?
- Multicellular
- Nucleus, membrane-bound organelles
- Chloroplasts & chlorophyll
- Cell wall of cellulose
- Most do not move
- Autotrophic feeders by photosynthesis
- Store food as starch
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What are the general features of Animalia?
- Multicellular
- Nucleus & other membrane-bound organelles
- NO cell wall
- No chloroplasts
- Move with cilia, flagella, contractile proteins
- Heterotrophic feeders - nutrients from ingestion
- Food stored as glycogen
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How does the Three Domain System group organisms?
- Differences in sequences of nucleotides in cells rRNA
- Cell membrane lipid structure
- Sensitivity to antibiotics
- Six kingdoms
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Which original kingdom from the 5 kingdoms is divided in two, and what are they called?
- Prokaryotae Becomes Archaebacteria and Eubacteria
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What are the differences between Archaebacteria and Eubacteria?
- Eubacteria contain peptidoglycan in cell walls
- Eubacteria (true bacteria) found in all environments
- Archaebacteria (ancient bacteria) live in extreme environments
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What is phylogeny?
The name given to the evolutionary relationships between organisms.
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What is phylogenetics?
The study of evolutionary history of groups of organisms.
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What are 'sister groups' on a phylogenetic tree?
Two descendants that split from the same node (common ancestor).
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Advantages to phylogenetic classification?
- Can be done without reference to Linnaean classification.
- Produces continuous tree and doesn't require organisms to be put in a group which they don't fit
- Gives idea of time scales
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What is evolution?
The theory that describes the way in which organisms evolve, or change over a period of time, as a result of natural selection.
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Who pioneered the theory of evolution?
Darwin and Wallace
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Evidence for evolution?
- Fossils (palaeontology)
- Comparative anatomy (similarities/differences between organisms' anatomy)
- Comparative biochemistry (similarities/differences between organisms' chemical makeup)
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Evidence provided by the fossil record:
- Earliest life forms found in oldest rock, matching ecological links to each other
- Gradual evolution from simple organisms to vertebrates over a long period of time
- Similarities in anatomy can be seen between organisms
- Show relationships between extinct and living organisms
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Disadvantages of Fossil Record as evidence:
- Incomplete - many soft-bodied organisms wouldn't have a chance to fossilise
- -incorrect conditions
- -fossils destroyed by earth, or still undiscovered
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What is a homologous structure?
- Structures that appear different, and may perform different functions, but have the same underlying structure.
- E.G. Vertebrate limbs can be used for running, jumping, flying, swimming, suggesting a common ancestor
- Provide evidence for divergent evolution
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Comparative Biochemistry as evidence:
- Some important molecules are highly conserved throughout evolution
- Cytochrome c (involved in respiration)
- rRNA
- Number of differences plotted against rate the molecule undergoes neutral base pair substitutions
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