Classification
- Nomenclature: naming of organisms
- Binomial: biological name of an organism → Genus species (eg Homo sapiens)
- Taxon: set of organisms within a category / taxonomy / study of biological classification
- Different levels of taxons: species, genus, family, order, class, phylum, kingdom
- Right side of spectrum → highest number of species
- Left side of spectrum → most similar organisms
- Five Kingdoms:
- Prokaryotae
- Protoctista
- Fungi
- Plantae
- Animalia
- Background Knowledge
- There is a new three-domain system:
- Domain Eukarya - contains the four kingdoms
- Animalia
- Pkantae
- Fungi
- Protista
- Domain Archaea
- Domain Bacteria
- Unicellular: Single cell; Colonial: Groups of cells; Multicellular: Many cells
- Autotrophs produce energy from inorganic sources
- Phototrophs from photosynthesis/sunlight
- Chemotrophs from simple inorganic (oxidative) processes
- Heterotrophs digest and absorb organic molecules
- Human classification
- Kingdom: Animalia (no cell wall, eat other organisms)
- Phylum: Chordata
- Class: Mammalia (produce milk from mammary glands)
- Order: Primates
- Family: Hominidae
- Genus: Homo
- Species: sapiens
Species
- Most basic unit of biological classification
- Members of a species are similar (phenotype) to each other but different from other species
- Similarity can be
- physical (branching pattern of trees)
- biochemical (haemoglobin structure)
- immunological (antibody against an antigen equally effective)
- development (similar growth of embryos)
- ecological (occupy identical ecological niche)
- Members of a species are able to reproduce giving fertile offspring
- Each species is reproductively isolated from every other species
- Prevents exchange of genes
- Species keep special characteristics that distinguishes them
Evidence of classification
- Biochemical
- Cytochrome c
- Protein used in cellular respiration and found in mitochondria
- Count number of amino acids that organisms differ by
- Higher number, more distant ancestor
- DNA hybridisation
- Unzip DNA from 2 different species
- Mix them to allow complementary base pairing
- Higher similarity, more base pairing, more energy required to separate hybrid DNA strands
- Anatomical
- Similar anatomical structure, more closely related
- Embryological
- Similar stages of development due to common ancestor
- Immunological
- Human blood serum is injected into a test animal
- Test animal recognizes foreign proteins (antigens) and produces antibodies
- Serum blood of immunized test animal is added to all test tubes
- Add human serum to one test tube (control)
- Add serum of other organisms to other test tubes (compare with control)
- Antigen-antibody complexes form and precipitate from solution
- Higher amount of precipitation, closer related to humans
- Behavioural
- Similar behaviour due to common ancestor
- Primates live in social groups, communicate by facial expression, long parental care
