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CLASSIFICATION

CLASSIFICATION

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CLASSIFICATION

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  1. CLASSIFICATION

  2. Sorting into groups 1. allows quick and accurate descriptions 2. simpler and precise communication 3. reference system for new organisms 4. enables trends to be observed and followed 5. explain relationships

  3. How classification has changed Ancient times Two groups, Plants and animals criteria : basic structure, leaves, roots etc for plants; no leaves, roots etc for animals 1737 - Carl Von Linné (Linnaeus) All natural objects (living and non-living) MINERALS concrete bodies without life and sensation VEGETABLES organised bodies with life and no sensation ANIMALS organised bodies with life, sensation and movement criteria: life and locomotion problem: assumes all animals are mobile and all plants are sessile

  4. 1838-39-Schleiden and Schwann - use of light microscope to see plant and animal cells Living things (composed of cells) ANIMAL Cell membrane, irregular shape, no chlorophyll PLANT Cell wall, regular shape, contain chlorophyll, large vacuole etc. criteria: structures in cell, biochemical processes, autotrophic nature of plants known, not yet understood problem: some unicellular organisms had flagella, allowing movement (animal) and chloroplasts (plant)

  5. 1866 -Haeckel - Created a kingdom for all microscopic unicellular organism Living things (composed of cells) ANIMAL Cell membrane, irregular shape, no chlorophyll PROTISTS Unicellular organisms PLANT Cell wall, regular shape, contain chlorophyll, large vacuole etc. criteria: structures in cell, including concept of independent cellular organisms, or dependent cells of tissues, organ etc. problem: contained both autotrophic and heterotrophic unicellular organisms in protista

  6. 1950’s -development of electron microscope PROCARYOTIC EUCARYOTIC Pro – simple Caryo – nucleus Have no distinct nucleus Eu – true Caryo – nucleus Have a distinct nucleus Procaryotes, simplest known form of life, believe they were the first type of cell to evolve. First appeared 3050 Myr ago and where the only living things for about 5500 Myr ANIMAL Cell membrane, irregular shape, no chlorophyll PROTISTS Unicellular organisms PLANT Cell wall, regular shape, contain chlorophyll, large vacuole etc. MONERA Procaryotic cells, no-membrane bound organelles criteria: structures in cell, biochemical pathways problem: fungi are they plant, autotrophic, or animal, heterotrophic

  7. 1967 -R.H. Whittaker Living things (composed of cells) ANIMAL Cell membrane, irregular shape, no chlorophyll PROTISTS Unicellular organisms PLANT Cell wall, regular shape, contain chlorophyll, large vacuole etc. MONERA Procaryotic cells, no-membrane bound organelles FUNGI Cell wall, no chloroplasts, saprophytic criteria: structures in cell and biochemical processes problem: unicellular autotrophic organisms – algae- now spread across two kingdoms, saprophytic bacteria also across two kingdoms 1964 -amino acid sequence determines protein and this amino acid sequence is determined by the sequence of bases in DNA

  8. This plus advances in cell biochemistry led to the discovery of two very distinct procaryotic groups. ARCHAEA BACTERIA Murein (disaccharide-amino acid complex) not present in cell wall Murein (disaccharide-amino acid complex) present in cell wall Lipids in cell membrane are branched Lipids in cell membrane are not branched Not sensitive to antibiotics Sensitive to antibiotics PROCARYOTES

  9. 1970 - six kingdoms Living things (composed of cells) ANIMAL Cell membrane, irregular shape, no chlorophyll FUNGI Cell wall, no chloroplasts, saprophytic PLANT Cell wall, regular shape, contain chlorophyll, large vacuole etc. PROTISTS Unicellular organisms MONERA Procaryotic cells, no-membrane bound organelles, cell wall contains murein ARCHAEA procaryotic cells, no murein in cell wall 1978 - ability to sequence DNA

  10. 1990 - Carl Woese - produced a radical, new classification system using three DOMAINS from which the major kingdoms developed criteria: biochemical comparisons i.e. comparison of the order of particular bases for particular genes in different organisms problem: major shift from traditional classification systems

  11. Can assist in reconstructing major events in evolution by comparing same gene from different organisms, allows the inference to be made each domain shows different lineages (kingdoms) branching off by comparing structural features and using fossil records, an inference is made as to the key events in evolution Another change occurs a change occurred producing two distinct lines First form of life

  12. SELECTION CRITERIA USED IN ALL CLASSIFICATION SYSTEMS. a set of characteristics which allows organisms to be identified use Keys most common a DICHOTOMOUS KEY divides into two at each branch using a yes or no question usually arranged as a flow diagram (tree) or table (sentence) Classify 13 non-identical objects Structural characteristics - Morphology do not change over time tend to find in groups if one structural characteristic is common more will be e.g. Vertebral column

  13. large number to choose from can show evolutionary patterns e.g. Pentadactyl limb

  14. Biochemical techniques. 1. Biochemical pathways: • use of radioactive isotopes • as they behave in reactions as normal atoms • can be detected, both qualitatively and quantitatively e.g. carbon-14 used to trace pathway of carbon through photosynthesis 2. Amino acid sequencing • proteins are made up of amino acid units • each protein has a unique number and sequence of amino acids • by comparing amino acid sequence the more similarities would indicate a closer evolutionary relationship e.g. cytochrome C: protein found in electron transport, shows only one difference between man and chimpanzee

  15. Biochemical techniques. 3. DNA sequencing: • sequence of bases encodes genetic information • greater similarity in sequence between organisms suggests closer evolutionary relationships • may also allow to trace the changes occurred to create the diversity of life Why are these criteria used? • unambiguous amino acid units • measurable

  16. MICROSCOPES LIGHT Identification of cellular structures – living things; plant and animals cells ELECTRON TRANSMISSION Identification of organelles – procaryotes and eucaryotes ELECTRON SCANNING 3-D structures of external structures TECHNOLOGY IN CLASSIFICATION SYSTEMS ELECTRON HIGH VOLTAGE TRANSMISSION Most recent, molecular level – arrangement of atoms in molecular materials

  17. BIOCHEMICAL TECHNIQUES Allows biochemical pathways to be observed - Energy source for methanogens, autotrophs etc. RADIO ISOTOPES AMINO ACIDS Allows comparison of complex proteins between organisms - The greater the similarity the closer the relationship Allows comparison of sequence of bases in DNA - The greater the similarity the closer the relationship DNA

  18. A hierarchical system assists classification. • hierarchy = a system organised into different levels • in classification these levels represent similarities between groups of organisms i.e. the levels of our current classification system are KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES contains a large number of organisms numbers in groups similarity increasing between groups contains only one type of organism • organisms in the same genus are more closely related than two organisms in the same family group

  19. KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES Animal Chordate Mammals Primate Hominoid Homo Sapien Heterotrophic, locomotion Vertebrate Suckle live young Forward thumbs and eyes No tail Walk on two legs Large forebrain BINOMIAL SYSTEM OF NAMES • accepted system • Linnaeussystem of a two word - binomial - name for all organisms e.g. Homo sapien (Homo sapien - ifwritten) genus species • genus refers to a similar group of organisms that do not interbreed

  20. species refers to: a group of organisms that are similar structurally, biochemically, behaviourally and are reproductively isolated producing live, fertile young – BASIC UNIT OF CLASSIFICATION A horse A donkey An Ass Infertile

  21. A tiger A Lion A Liger Infertile Very closely related but not from same species More modern definitions of species includes number and shape of chromosomes

  22. Advantages of scientific naming 1. universal language 2. removes common name variation e.g. prickly Moses Western Australia for Acacia pulchella New South Wales for Acacia ulicifolia Vic and Tas Acacia verticillata

  23. 3. can indicate degree of relatedness e.g. Macropus genus kangaroo species giganteus(eastern grey) rufus (red) fulginosus (western grey) show similar morphology, physiology, biochemistry and phylogeny (evolution) which is reflected in their scientific name 4. removes misleading common names eg cuttlefish are not fish but molluscs