Classification Flashcards
Classification
The process of sorting living things into groups. Natural classification does this by grouping things according to how closely related they are, reflecting evolutionary relationships. Puts similar organisms into groups based on shared similarities (e.g. anatomy, physiology, embryology, fossil record). Groups are taxa (one is a taxon). Series of smaller and smaller groups called a heirachy
Phylogeny
The study of the evolutionary relationships between organisms - can classify according to these. Shows how closely related different species are - how recently they shared a common ancestor.
Taxonomy
The study of the principles of classification. Each group is called a taxon. E.g. groups are kingdom, phylum etc. Helps us understand our evolution
Relationship between classification and phylogeny
Classification is the process of placing living things into groups. Phylogeny is the study of evolutionary relationships. These relationships can be used to classify living things with other species with whom they shared a common ancestor with most recently.
Taxonomic heirachy
Domain, kingdom, phylum, class, order, family, genus, species
Characteristic features of prokaryotae
- Mostly unicellular
- No nuclei; DNA in circular loop not bound to proteins or arranged in linear chromosomes
- Cell wall made of peptidoglycan
- No membrane bound organelles; smaller ribosomes
- Autotrophic and heterotrophic nutrition
- Some have flagella for mobility
- No nervous co-ordination
Characteristic features of protoctista
- Unicellular and multicellular
- Have a nuclei
- Some have cell walls, which may be made of cellulose
- Have organelles
- Autotrophic and heterotrophic nutrition
- Some have cilia (undulipodium)
- No nervous co-ordination
Characteristic features of fungi
- Network of strands called hyphae (many is mycelium): apart from yeast
- Cytoplasm not divided into cells
- Have many nuclei (multinucleate)
- Cell wall made of chitin
- Has organelles, but no chloroplasts
- Heterotrophic nutrition (feed using extracellular enzymes: saprophytic)
- No motility
- No nervous co-ordination
Characteristic features of plantae
- Multicellular
- Have nuclei
- Cell wall made of cellulose
- Have organelles, including chloroplasts
- Autotrophic nutrition
- No motility
- No nervous co-ordination
Characteristic features of animalia
- Multicellular
- Have nuclei
- No cell wall
- Have organelles, but no chloroplasts
- Heterotrophic nutrition
- Can move
- Have nervous co-ordination
System of binomial nomenclature
Uses 2 names to identify each species: genus name and species name.
Development of classification systems
- Used to be based on observable features
- As technology developed, new discoveries were made, and this was incorporated into the classification systems: they changed to reflect this.
- Scientists will never agree
Comparing 5 kingdoms to 3 domains
-3 domains system was made when it was realised that some prokaryotes were different from others, so the group ought to be divided: there were differences in cell membrane, flagella, RNA polymerase, genetic material and proteins, DNA replication etc. Were divided into 3 domains: Eukarya, Eubacteria and Archaea
