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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
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
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
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
What are the 5 kingdoms?
- ProkaryotaeProtoctista FungiPlantaeAnimalia
What are the general features of Prokaryotae?
- 'the prokaryotes'
- No nucleus or membrane-bound organelles
- No visible feeding mechanism - nutrients either absorbed or produced internally e.g. by photosynthesis
What are the general features of Protoctista?
- (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
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
What are the general features of Plantae?
- Nucleus, membrane-bound organelles
- Chloroplasts & chlorophyll
- Cell wall of cellulose
- Most do not move
- Autotrophic feeders by photosynthesis
- Store food as starch
What are the general features of Animalia?
- 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
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
Which original kingdom from the 5 kingdoms is divided in two, and what are they called?
- Prokaryotae Becomes Archaebacteria and Eubacteria
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
What is phylogeny?
The name given to the evolutionary relationships between organisms.
What is phylogenetics?
The study of evolutionary history of groups of organisms.
What are 'sister groups' on a phylogenetic tree?
Two descendants that split from the same node (common ancestor).
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
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.
Who pioneered the theory of evolution?
Darwin and Wallace
Evidence for evolution?
- Fossils (palaeontology)
- Comparative anatomy (similarities/differences between organisms' anatomy)
- Comparative biochemistry (similarities/differences between organisms' chemical makeup)
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
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
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
Comparative Biochemistry as evidence:
- Some important molecules are highly conserved throughout evolution
- Cytochrome c (involved in respiration)
- Number of differences plotted against rate the molecule undergoes neutral base pair substitutions