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Domain Bacteria and Archea Prokaryotes • A prokaryote is a single-celled organism that lacks a nucleus. • “___________ bacteria are prokaryotes!” • Remembering classification – Domain Bacteria – Domain Archea – Domain Eukarya Domain Archea • Kingdom Archeabacteria – Lack peptidoglycan – DNA in genes is more similar to eukaryotes than bacteria – Harsh environments • Three Types: – Methanogens – Halophiles – Thermophiles Halophilic • • • • “salt-loving” Photosyntheic Autotrophic Use Pigment bacteriorhodopsin that uses all light except for purple light, making the cells appear purple. Thermophilic • Hot springs and thermal vents • Anaerobic=Don’t use oxygen • contain genes for heatstable enzymes • An example is taq polymerase, the gene for which was isolated from a collection of Thermus aquaticus in a Yellowstone Park hot spring. • Taq polymerase is used to make large numbers of copies of DNA sequences in a DNA sample. • Annual sales of taq polymerase are roughly half a billion dollars! Methanogens • These archeabacteria are anaerobes. • They make methane (natural gas) as a waste product. • swamp sediments, sewage, and in buried landfills. • Bioremediation in landfills Domain Bacteria • Bacteria are of immense importance because of their rapid growth, reproduction, and mutation rates, as well as, their ability to exist under adverse conditions. • The oldest fossils known, nearly 3.5 billion years old, are fossils of bacteria-like organisms. Autotrophs or heterotrophs • Those that are classified as autotrophs are either photosynthetic, obtaining energy from sunlight or chemosynthetic, breaking down inorganic substances for energy . Heterotrophic Bacteria • breaking down complex organic compounds in the environment. • saprobes: bacteria that feed on decaying material and organic wastes, • Parasites: absorbing nutrients from living organisms. Eubacteria- “true” bacteria • Live almost everywhere • Have no organelles • Peptidoglycan in cell walls • Cell wall • Cell membrane within the cell wall Short Video Structure of Bacteria See coloring sheet • The Gram stain, which divides most clinically significant bacteria into two main groups, is the first step in bacterial identification. • Bacteria stained purple are Gram + - their cell walls have thick petidoglycan and teichoic acid. • Bacteria stained pink are Gram – their cell walls have have thin peptidoglycan and lipopolysaccharides with no teichoic acid. 3 Types of Bacteria Bacilli- rod shaped Cocci- spherical Spirilla- spiral shaped Bacterial Growth and Reproduction • Bacteria can reproduce sexually by conjugation or asexually by binary fission. Are bacteria bad? (no) Cyanobacteria were the first organisms on Earth to do modern photosynthesis and they made the first oxygen in the Earth's atmosphere. • Bacteria are often maligned as the causes of human and animal disease. However, certain bacteria, the actinomycetes, produce antibiotics such as streptomycin and nocardicin. • Still other Bacteria live on the roots of certain plants, converting nitrogen into a usable form. • Nitrogen-fixing bacteria • Bacteria put the tang in yogurt and the sour in sourdough bread. • Saprobes help to break down dead organic matter. • Bacteria make up the base of the food web in many environments. Streptococcus thermophilus in yogurt • Bacteria are prokaryotic and unicellular. • Bacteria have cell walls. • Bacteria have circular DNA called plasmids • Bacteria can be anaerobes or aerobes. • Bacteria are heterotrophs or autotrophs. • Bacteria are awesome and all over the place!!!