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5 Kingdom System vs. 3 Domain System Previously the diversity of life was classified based on 5 kingdoms 1. Monera (prokaryotes) 2. Protists (simple eukaryotes) 3. Plants (autotrophic eukaryotes) 4. Fungus (heterotrophs who act as decomposers) 5. Animals (heterotrophs who consume their food) 5 Kingdom System vs. 3 Domain System Because of evolutionary analysis, most scientists have adopted a 3 domain classification system over the 5 kingdom system. Monera is now divided between the Domains Bacteria and Archaea. Protists, plants, fungi, and animals are in the Domain Eukarya. Let’s Review Prokaryotes… Structure: unicellular with no nucleus, no membrane bound organelle - cell wall with or without peptidoglycan -can have flagella made of flagellin (not microtubules like in eukaryotes) - common shapes include round, rod or spiral shaped Heredity Material: circular DNA chromosome supplemented with plasmids Reproduction: asexual by binary fission Let’s Review Prokaryotes… Nutrition: (How They Obtain their Organic Compounds) Photoautotrophs- manufacture organic compounds using light Chemoautotrophs- manufacture organic compounds using inorganic chemicals (NH3, H2S) Heterotrophs- consume organic compounds • Some may be parasites (feed on living organisms) • Some may be saprobes or saprophytes (feed on decaying matter) Survival With or Without Oxygen: Obligate Aerobes (require O2) Facultative Aerobes (will use O2 if available) Obligate Anaerobes (require no O2) Domain Bacteria or Eubacteria • The majority of bacteria that people come in contact with such as pathogenic bacteria or the bacteria in yogurt • Categorized by their modes of nutrition, shape, and motility Some Examples of Bacteria Anthrax is a bacteria that will produce endospores when stressed. The endospores are hard shells that surround a copy of the DNA. The bacteria disintigrates and leaves behind the spore. The spore has to be heated to 121 degrees Celsius in order to be killed. Cyanobacteria are the only photoautotrophic prokaryotes. They were formally called “bluegreen algae” but that nomenclature has been abandoned because algae are eukaryotes. Some Examples of Bacteria Bacteria can convert or “fix” nitrogen gas which can’t be used by plants into ammonia that can be used by plants. The plants then convert the nitrogen into amino acids and other organic compounds. Domain Archaea or Archaebacteria • Share traits with both bacteria and eukarya • “extremophiles”- live in extreme conditions • 3 Most Common Types Domain Archaea 1) Methanogens- anaerobic heterotrophic bacteria that make methane • Found in sewage treatment facilities, the guts of ruminants such as cattle, hot springs Domain Archaea 2) Extreme Halophiles- “salt lovers” • Found in salt lakes and salted food Commercial Salt Ponds Great Salt Lake Domain Archaea 3) Extreme Thermophiles- “heat lovers” • Found in hot springs and volcanic vents Grand Prismatic Springs at Yellowstone Deep Ocean Vents Domain Eukarya Kingdom “Protista” • Diverse group of organisms that were lumped together into a kingdom because they didn’t fit into the other kingdoms • Can be multicellular or unicellular • Can be plant-like, fungus-like, or animal like “Protists” • Kingdom Protista is not based on evolutionary relationships • It is now not accepted because we now know that some protists are more closely related to plants and animals than other protists Domain Eukarya Kingdom “Protista” Plant-like Animal-like Fungus-like Fungus-Like Protists • They form filaments or make spores, like fungi. Water Mold on a Dead Fruit Fly Slime Mold: Closely related to Fungi Protozoa: “Animal-Like Protists” • Heterotrophs that feed on other organisms (dead or alive) Paramecium Amoeba Trypanosoma causes sleeping sickness. Protozoa Example: Malaria Parasite Plant-like Protists • Carry out photosynthesis Dinoflagellates Diatoms Euglena Plant-like Protists Three Types of Algae Giant Kelp Nori 2) Phaeophyta or Brown Algae 1) Rhodophyta or Red Algae Sea Palm Plant-like Protists:Three Types of Algae 3) Chlorophyta or Green Algae It is believed that green algae and land plants share a common ancestor. • Use chlorophyll a and b, have cellulose in their cell walls, and store sugars in the form of starch, all like plants. Ulva Volvox
