Chapters 16-19: Diversity of Life 1. Taxonomic Classification 2. Viruses and Prokaryotes 3. Protists and Fungi 4. Plants 5. Animals
1. Taxonomic Classification
The Classification of Organisms There are ~1.5 million known species on our planet. total # or species on earth estimated to be anywhere from 7 to 100 million To study so many organisms and their evolutionary relationships requires: standard nomenclature same name used worldwide for a given organism hierarchy, system of classification allows organization by relatedness
The Taxonomic Hierarchy Each level of the hierarchy is referred to as a taxa: Domain Kingdom Phylum Class Order Family Genus Species Humans eukarya animal chordates mammals primates hominids Homo sapiens
The Major Taxa The 3 Domains: 4 Kingdoms of Eukarya: Bacteria Archaea Eukarya Protists, Fungi, Plants & Animals
Bacteria: common prokaryotes Archaea (or archaebacteria): unusual prokaryotes or extremophiles thrive in harsh environments (acid, high salt, boiling ) Eukarya: all organisms made of eukaryotic cells Protists: single-celled eukaryotes Fungi: multicellular; absorb food Plants: multicellular; photosynthesize Animals: multicellular; ingest food
2. Viruses and Prokaryotes
Viruses are Small, Simple, Non-living Consist of genetic material (DNA or RNA) inside a protein coat (may have a membrane envelope). no metabolic capabilities reproduce only within a host frequently lyse or kill host cell euk. cell bacteria viruses
Viruses come in Immense Variety Differ in: size & shape genetic material DNA, RNA, double or single strand mode of infection host specificity
AIDS Virus Infection The AIDS virus is a retrovirus: must convert RNA to DNA
Types of Prokaryotes Prokaryotes = single-celled organisms lacking nuclei and other organelles Bacteria live in every conceivable environment immense variety of metabolism, physiology play many essential biological roles nitrogen fixation (all plants depend on it!) decomposition (essential for recycling of nutrients) digestion (gut flora in humans, cattle, ) Archaea thrive in very extreme environments
Prokaryotes come in 3 Basic Shapes spherical (coccus) rod-shaped (bacillus) corkscrew-shaped (spirillum)
3. Protists and Fungi
Types of Protists Protists = most single-celled eukaryotic organisms some can form multicellular aggregates 2 basic types of protist: 1) Protozoa ( first animals ) heterotrophs (ingest food) amoebae, paramecia, zooplankton, trypanosomes many are parasites e.g., trypanosomes, plasmodium (causes malaria) trypanosomes
2) Algae ( photosynthetic protists ) phytoplankton seaweeds (dinoflagellates, diatoms, volvox) diatoms seaweed (kelp) volvox
The Fungi Types of Fungi include: molds yeast mushrooms
Key Characteristics of Fungi Fungi digest organic material externally (they don t ingest food like animals do): secrete digestive enzymes, absorb food some are detritus feeders (consume dead matter) some are parasites (prey on living) decomposition of dead organic matter is extremely important for ecosystems (recycles nutrients) Fungal cells have cell walls (made of chitin) Can reproduce sexually or asexually
4. Plants
What constitutes a Plant? Plants are multicellular, photosynthetic, and share characteristic modes of reproduction Major plant phyla, classes
The Bryophytes Liverworts Mosses Key features: lack true leaves, roots, stems no internal vasculature rely mainly on diffusion limits their size
The Tracheophytes Tracheophytes are the vascular plants: contain vessels to transport material internally There are 3 basic types of vascular plant: seedless vascular plants (e.g., ferns, horsetails) gymnosperms (all cone-bearing plants) angiosperms (all flowering plants)
Horsetails Seedless Vascular Plants most primitive vascular plant Ferns
Gymnosperms pine All cone-bearing plants: conifers (pines, firs, etc ), cycads, gingko seeds produced in cones (not flowers) cycad juniper gingko
Angiosperms All flowering plants: produce seeds* in flowers (via fertilization of gametes) disperse seeds via fruits *seeds are plant embryos + nutrients within a seed coat most dominant type of plant
5. Animals Invertebrates Vertebrates
Characteristics of Animals All members of the Animal Kingdom: are multicellular consist of eukaryotic cells w/o cell walls are heterotrophs consume food derived from other organisms feed by ingesting food unlike fungi which absorb food externally Most members of the Animal Kingdom: have a symmetrical body plan radial or bilateral symmetry have distinct tissues, organs reproduce sexually
symmetry as viewed from the dorsal (back) or ventral (belly) sides Radial vs Bilateral Symmetry Radial Symmetry symmetrical halves no matter how you slice it Bilateral Symmetry only one plane of symmetry
Vertebrate vs Invertebrate Vertebrate animals have a backbone or vertebral column less than 3% of known animal species Invertebrate animals NO backbone or vertebral column > 97% of known animal species any non-vertebrate animal The vertebrate/invertebrate distinction is somewhat old school They more or less constitute sub-kingdoms
Major Invertebrate Phyla Lower Invertebrates Porifera all sponges Cnidarians anemones, coral, jellyfish Platyhelminthes all flatworms Nematodes all roundworms Higher Invertebrates Annelids all segmented worms Mollusks snails, clams, squids Arthropods insects, spiders, crabs Echinoderms starfish, sea urchins
***All vertebrates are chordates but not all chordates are vertebrates*** The Phylum Chordata Main characteristics of the Chordates: have a notochord usu. gives rise to the backbone during development have a hollow nerve cord becomes brain & spinal cord during development pharyngeal gill slits may disappear during development have a tail may disappear during development
Major Chordate Classes Agnatha jawless fishes Chondrichthyes cartilagenous fishes Osteoichthyes bony fishes Reptiles lizards, snakes, turtles Birds (Aves) chickens, eagles Mammals humans, cats, dogs Amphibians frogs, salamanders
Key Terms for Chapters 16-19 taxa, domain, kingdom, phylum bacteria, archaea, eukarya, fungi, protists bacillus, coccus, spirillum protozoa, algae bilateral vs radial symmetry, vertebrate vs invertebrate Relevant Review Questions: ch. 16 3, 6; ch. 17 3, 5, 9 ch. 18 1, 3-5, 7-15; ch. 19 3