classification 2

Classification 2

Binomial Naming System: two names to identify each species: genus and species.
Dichotomous key: series of qus with two alternative answers to help identify specimen
Early classification systems only used observable features:
- Molecular evidence - similarities in proteins and DNA. More closely related organisms will have more similar molecules. Sequence of DNA bases, sequence of amino acids in proteins from different organisms. More similar = more related
- Embryological evidence - similarities in early stages of organism's development
- Anatomical evidence - similarities in structure and function of different body parts
- Behavioural evidence - similarities in behaviour and social organisation of organisms

Three domains: Cells that contain a nucleus are placed in the domain Eukarya. Organisms that were in Prokaryotae are separated into to new kingdoms: Archaea and Bacteria.
- New evidence, mainly molecular, reclassified as two domains showed large differences between Archaea and Bacteria.
- Molecular = enzyme RNA polymerase is different in Archaea and Bacteria.
- Archaea have similar histones to Eukarya
- Cell membrane evidence - bonds in B and A different. Composition of flagella different

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Biological classification is the process of sorting living things into groups. Natural classification does this by grouping things on how closely related they are. reflects evolutionary relationships.
Taxonomy is the study of the principles of classification.
Phylogeny is the study of the evolutionary relationships between organisms. All have evolved from a common ancestor. More recent relative = more closely related
Monophyletic: belong to the same phylogenetic groups
Taxonomic hierarchy: Domain, Kingdom, Phylus, Class, Order, Family, Genus, Species
Autotrophic Nutrition: organism makes its own food from simple inorganic molecules
Heterotrophic Nutrition: gains nutrients from complex organic molecules

Prokaryotae: e.g. bacteria: prokaryotic, unicellular, no nucleus, less than 5 micrometres, naked DNA chromosomes, no membrane-bound organelles, smaller ribosomes
Protoctista: e.g. algae: eukaryotic, mostly single-celled, wide variety of forms, plant and animal features, mostly free-living, autotrophic and heterotrophic nutrition
Fungi: eukaryotic, mycelium with hyphae, cell walls made of chitin, multinucleate
Plantae: eukaryotic, multicellular, cellulose cell wall, autotrophic nutrition
Animalia: eukaryotic, multicellular, heterotrophic nutrition, fertilised eggs, usually mobile

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