prokaryotes

prokaryotes - Kingdoms and Domains When Linnaeus developed...

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Unformatted text preview: Kingdoms and Domains When Linnaeus developed his system of classification, there were only two kingdoms, Plants and Animals. But the use of the microscope led to the discovery of new organisms and the identification of differences in cells. A two kingdom system was no longer useful. Today the system of classification includes six kingdoms. Kingdoms and Domains 5 Kingdom system (Whittaker 1969) Monera bacteria and cyanobacteria Protista protozoa, algae, slime molds Fungi molds, yeasts Plantae plants Animalia animals Kingdoms and Domains Carl Woese U. of Illinois (1970's present) studied gene sequences of bacteria, archaea, and eukaryotes found major fundamental differences Kingdoms and Domains 6 Kingdom system (mid 1970's) Eubacteria Archaea The two groups differ biochemically split Monera (or Prokaryotae) into: and genetically from each other Kingdoms and Domains How are organism placed into their kingdoms? Cell type, complex or simple How they obtain energy Autotroph Heterotroph The number/types of cells in their body Life can be divided into three domains: The Prokaryotes Kingdoms/Domains Archaea and Eubacteria Prokaryotes Most abundant organisms on Earth Billions in a tablespoon of soil Ubiquitous (found everywhere) Soil, air, water, inside and on other organisms Can inhabit harsh environments boiling hot geysers hot acid pools deep in rock layers (2 miles or more) Size: Microscopic, but some can reach almost over half a millimeter in size! Epulopiscium fishelsoni lives in the guts of Surgeon Fish Prokaryotes Singlecelled organisms Basic shapes Rods (bacilli) Spheres (cocci) Spirals (spirilli) Also: cubes, stars etc. Prokaryotes Simple structural plan No nucleus or organelles distinguishes prokaryotes from eukaryotes Prokaryotes Reproduce by binary fission (asexual) How old are they? Banded IronFormation (BIF) constitutes the majority of the world's iron deposits. Date from 1.8 2.5 bya in the Lake Superior region Others date to over 3.5 bya Most commonly these deposits consist of alternating layers of black hematite and red stained chert (iron oxides = rust). Banded Iron-Formation Vast quantities of iron entered the ocean surface through volcanic action, upwelling, and runoff. During much of the Precambrian the Earth's surface waters and the atmosphere were anaerobic (oxygen free) so that iron would exist mostly in its soluble form. BIF deposits are a direct result of oxygen release by Precambrian microbes. Photosynthesis by cyanobacteria in the surface waters produced oxygen which reacted with the iron to precipitate out iron hydroxide (rust). Banded Iron-Formation Seasonal and/or biological cycles resulted in intervening periods when iron or oxygen were not as available resulting in the interlayered chert (microcrystalline quartz precipitate). How old are they? Oldest known fossil bacteria are about 2.8 billion years old Look like cyanobacteria suggesting ancient origin for photosynthesis Cyanobacteria fossils from stromatolites date to 2.8 to 2.5 bya (maybe older) Filamentous strands of cells resembling modern Stromatolites still exist as living fossils species of Oscillatoria or Lyngbya Stromatolites Layered mounds of calcareous material between cyanobacterial cells. Following 3 slides show fossil stromatolites Closest place to find these: Upper Peninsula of Michigan Upper Peninsula of Michigan Stromatolite Formation The layers were produced as calcium carbonate precipitated over the growing mat of bacterial filaments. Photosynthesis by the cyanobacteria depleted carbon dioxide in the surrounding water, initiating precipitation of calcium carbonate. The minerals, along with grains of sediment precipitating from the water, were then trapped within the sticky layer of mucilage that surrounds the bacterial colonies, which then continued to grow upwards through the sediment to form a new layer. As this process occured over and over again, the layers of sediment were created. Stromatolite formation still occurs today; Shark Bay in western Australia is well known for the stromatolite "turfs" rising along its beaches. Marine, low latitude, hypersaline environment. Fossil Oscillatoria Living Oscillatoria Palaeolyngbya also from the Bitter Springs chert. Living Lyngbya Lyngbya Colonial chroococcalean cyanobacterium from the Bitter Springs chert of central Australia, a site dating to the Late Proterozoic, about 850 million years old. Floating mat of cyanobacterium from around a hot spring Fossilized cyanobacterial mat Archaea Archaea The Archaea have a diverse variety of shapes and exist not only as rods and dots (cocci) like bacteria but also as triangles, discs, plates and cupshapes. Archaea build the same cellular structures as other organisms, but they build them from different chemical components. (1) Halophiles in salty lakes, (2) Thermoproteus in deep sea hydrothermal vents, (3) Sulfolobus in hot sulfur springs, (4) Methanococcus in swamps and marshes, and (5) Acidianus in acidic ponds. Archaea There are three types of archaea, the most ancient of all living things. Archaea can be organized into three types based on their physiology: extreme (hyper) thermophiles (procaryotes that live at very high temperatures) methanogens (procaryotes that produce methane) extreme halophiles (procaryotes that live at very high concentrations of salt (NaCl) Extreme Thermophiles Several distinct phylogenetic lines of Archaea. These organisms require a very high temperature (80 degrees to 105 degrees centigrade) for growth. The high temperature species occur naturally in volcanic vents and deep ocean hydrothermal vents as well as in manmade habitats such as the effluent from Geothermal power stations. The thermoacidophiles live in the extremely hot, acidic water and moist areas within and surrounding sulfur hot springs. So closely adapted are they to their environment that they die of cold at temperatures of 55C (131F)! Great Prismatic Spring Yellowstone NP Methanogens Methane Producing Archaea Found in anoxic sediments and swamps, lakes, marshes, paddy fields, landfills, hydrothermal vents and sewage works as well as in the rumen of cattle, sheep and camels, the cecae of horses and rabbits, the large intestine of dogs and humans, and in the hindgut of insects such as termites and cockroaches. Methanogens Methanogens obligate anaerobes (free oxygen kills them) cannot tolerate even brief exposure to oxygen produce methane (CH4) as a waste product during cellular respiration. The reason you can ignite a puff of flatulence (should you choose to go into show business) is because of the symbiotic methanogens inside your guts. Methane is a greenhouse gas that may contribute to global warming because it is increasing in concentration in the atmosphere. Methanococcus jannischii Extreme Halophiles Found in extremely saline or salty environments as the Dead Sea, the Great Salt Lake and evaporating ponds of seawater where the salt concentration is very high (as high as 25% NaCl). Also found in highly salted foods such as salted fish. Their pink carotenoid pigments make them conspicuous when the bacteria are present in large concentrations, as they are on the shores of some salty, landlocked lakes. Eaten by brine shrimp which are eaten by flamingos; makes their feathers pink Evidence suggests Archaea are more similar to Eukarya than to Eubacteria Eubacteria cell membrane Cell wall DNA Bacteria Cell walls in eubacteria Grampositive Very thick peptidoglycan Gramnegative Thin peptidoglycan layer Outer membrane Capsule Sometimes surrounds the entire cell wall Protection against phagocytosis C.M. = cytoplasmic membrane Bacteria Pili Protein structures that extend from the cell Help bacteria adhere to surfaces Bacteria Flagella Produce a rotary motion like a propeller Go forward by rotating one direction Go backwards by reversing rotation. Salmonella bacteria with peritrichous flagella. TEM X13,250. Bacteria Genetic material Asexual reproduction Binary fission Budding Fragmentation Circular DNA molecule Plasmids Bacteria BACTERIA CAN DO EVERYTHING EVERYWHERE Key to the success of prokaryotes is their diverse physiology Many different ways to obtain and use nutrients. Some require oxygen (aerobes) Some can live without oxygen (anaerobes) Some can live with or w/o oxygen (facultative anaerobes) Some can withstand long periods of drying as endospores. Bacillus anthracis Anthrax Bacteria showing an endospore. The function of bacterial endospores is survival under harsh environmental conditions, not reproduction. They may remain dormant for long periods. TEM X41,000. Photosynthesis Ecological Importance of Bacteria Some can be producers in ecosystems They are autotrophs: self feeders The cyanobacteria (bluegreen algae) carry out photosynthesis exactly the same way as plants. Single celled cyanobacteria gave rise to the chloroplast. Plants need nitrogen to grow, but they cannot use nitrogen gas from the air. Certain bacteria can capture nitrogen from the air and turn it into a form plants can use through a process called Nitrogen Fixation. Bacteria capture nitrogen from the air and makes it available for plants as nitrate. Some of these bacteria live in nodules on the roots of legumes (beans, peas). Other types live freely in the soil. Ecological Importance of Bacteria Nitrogen Cycle Root Nodule and Rhizobium Nutrient recycling Ecological Importance of Bacteria Performed by heterotrophic bacteria Decomposition of dead organisms Decomposition of urine and feces Help clean up oil spills Sewage treatment plants Before Before After Bacteria and Humans Mutualism (a type of symbiosis) E. coli in our intestine produce vitamin K We cannot make this vitamin ourselves Vit K is necessary for blood clotting Bacteria in our mouth, reproductive tract, intestines, and on our skin help protect us from harmful bacteria. Vaginal bacteria help prevent yeast infections. E. coli Bacteria and Humans Pathogens Organisms that cause disease in plants, humans, and other animals. Waterfowl killed by botulism Clostridium botulinum Streptococcus pyogenes Bacteria and Humans Produce many useful products Antibiotics e.g. Streptomycin Foods Vinegar Yogurt Cheese Municipal Water Treatment Trickling Filter Biofilms Biofilm containing diatoms and bacteria Activated Sludge Figure 27.20a,b Anaerobic Sludge Digester Decomposition by Microbes Great Prismatic Pool Only at the center of the image, where the blue water is, is the temperature too hot for any species to survive, but as the water streams away from the pool, it cools and is populated by a differentially temperatureoptimized species of cyanobacteria, forming surprisingly thick microbial mats. ...
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This note was uploaded on 06/23/2011 for the course BIO 112 taught by Professor Dr.dertein during the Spring '11 term at St. Xavier.

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