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Prokaryotes Chapter 27 Quic kTime™ and a dec ompres sor are needed to see this pic ture. • Earliest organisms on Earth - evolved alone for 1.5 billion years. • More prokaryotes inhabit a handful of fertile soil or the mouth or skin of a human than the total number of people who have ever lived. QuickTime™ and a decompressor are needed to see this pict ure. The vivid reds, oranges, and yellows that paint these rocks are colonies of prokaryotes. • Types of diseases caused by bacteria - tuberculosis, cholera, many sexually transmissible diseases, certain types of food poisoning. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. http://news.bbc.co.uk/olmedia/1825000/images/_1827130_tb_bacterium300.jpg QuickTime™ and a decompressor are needed to see this picture. TB Bacteria • Most bacteria benign or beneficial. • Bacteria in intestines produce vitamins. • Prokaryotes recycle carbon, other elements between soil and atmosphere. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. • Mitochondria, chloroplasts evolved from prokaryotes - became residents in host cells. QuickTime™ and a decompressor are needed to see this picture. http://www.botany.hawaii.edu/faculty/webb/Bot201/Hornworts/AnthEpiSurfCplast.jpg http://www.botany.hawaii.edu/faculty/webb/Bot201/Hornworts/AnthEpiSurfCplast.jpg QuickTime™ and a decompressor are needed to see this picture. • 2 prokaryotic domains (above kingdom): Bacteria and Archaea • Archaea inhabit extreme environments - differ from bacteria in structural, biochemical, and physiological characteristics. QuickTime™ and a decompressor are needed to see t his picture. QuickTime™ and a GIF decompressor are needed to see this picture. • Most prokaryotes - unicellular. • Some aggregate for period of time or form colonies. • Shapes - spheres (cocci), rods (bacilli), helices (spirochetes). QuickTime™ and a d eco mpres sor are nee ded to s ee this picture . • Cell wall maintains shape, physical protection, prevents cell from bursting. • Most bacterial cell walls contain peptidoglycan, (polymer of sugars and polypeptides) • Archaea lack peptidoglycan. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://msnbcmedia3.msn.com/j/msnbc/Components/Photos/050207/050207_livesci_extremophiles_hmed11a.hlarge.jpg QuickTime™ and a decompressor are needed to see this picture. • Gram stain - identifies bacteria based on differences in cell walls. • Gram + have simpler cell walls, large amounts of peptidoglycans. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. • Gram - have more complex cell walls, less peptidoglycan - outer membrane contains carbohydrates bonded to lipids. • More threatening than grampositive species. QuickTi me™ a nd a de com press or are need ed to se e th is p icture. • Gram-negative bacteria more resistant to antibiotics - outer membrane impedes entry of antibiotics. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://jon9783.myweb.uga.edu/image/image1.jpg E. coli QuickTime™ and a decompressor are needed to see this picture. • Many prokaryotes secrete sticky protective layer - capsule. • Glue together cells of prokaryotes that live as colonies. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://www.olympusmicro.com/micd/galleries/darkfield/bacterialcapsules.html QuickTime™ and a decompressor are needed to see this picture. • Pili fastens pathogenic bacteria to mucous membranes of host. • Some specialized for holding 2 prokaryote cells together to transfer DNA during conjugation. QuickTime™ and a decompressor are needed to see this pict ure. • Most common form of movement flagella. • 2nd found in spirochetes - filaments - moves like a corkscrew. • 3rd occurs in cells that secrete slimy threads - glides along at growing end of threads. QuickTi me™ and a decompressor are needed to see thi s pi ctur e. • Capable of taxis (chemotaxis, phototaxis) QuickTime™ and a d eco mpres sor are nee ded to s ee this picture . http://www.brineshrimpdirect.com/contentimages/brineshrimp_photo3.jpg QuickTime™ and a decompressor are needed to see this picture. • Prokaryotic cells lack nucleus, internal compartments bounded by membranes like eukaryotes. • Use infolded regions of plasma membrane to perform metabolic functions (cellular respiration, photosynthesis) Quic kTime™ and a dec ompres sor are needed to see this pic ture. • Simpler genomes than eukaryotes DNA concentrated as fibers in nucleoid region. • Single prokaryotic chromosome double-stranded DNA molecule in form of ring. • May also have smaller rings of DNA (plasmids) consist of only a few genes. Qui ckTime™ and a decompressor are needed to see thi s pi cture. http://student.biology.arizona.edu/honors2000/group10/ plasmid.gif QuickTime™ and a decompressor are needed to see this picture. • Prokaryotes reproduce asexually binary fission. • Transformation - cell can absorb, integrate fragments of DNA from environment. • Conjugation - directly transfers genes to another cell. • Transduction - viruses transfer genes between prokaryotes. QuickTime™ and a decompressor are needed to see this pict ure. • Prokaryote can withstand harsh conditions. • Bacteria form resistant cells endospores - cell replicates chromosome, surrounds one chromosome with durable wall. • Can survive lack of nutrients and water, extreme heat or cold, and most poisons. Quic kTime™ and a dec ompres sor are needed to see this picture. http://www.apsnet.org/education/illustratedglossary/PhotosE-H/endospore.jpg QuickTime™ and a decompressor are needed to see this picture. • When conditions favorable hydrates and becomes active. • Microorganisms release antibiotics to inhibit growth of other microorganisms (prokaryotes, protists, and fungi) because of competition for space. • Humans use these to kill bacteria. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://www.lausd.k12.ca.us/Figueroa_EL/images/Mystery%20to%20Medicine/antibiotics.jpg QuickTime™ and a decompressor are needed to see this picture. • Prokaryotes grouped according to how they obtain nutrition. • 1Light energy - phototrophs. • 2Energy from chemicals in environment -chemotrophs. • 3Need only CO2 as carbon source autotrophs. • 4Require organic nutrient as carbon source - heterotrophs. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. http://www.clcbio.com/scienceimages/cyanobacteria.png QuickTime™ and a decompressor are needed to see this picture. • Further divided based on what they use. • 1Photoautotrophs - photosynthetic light energy to synthesize organic compounds from CO2. • Photoautotrophic prokaryotes cyanobacteria. • Photosynthetic eukaryotes - plants and algae. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. http://www.astrographics.com/GalleryPrints/Display/GP 2028.jpg QuickTime™ and a decompressor are needed to see this picture. • 2Chemoautotrophs need CO2 as carbon source, obtain energy by oxidizing inorganic substances, not light - i.e. hydrogen sulfide (H2S), ammonia (NH3) • Unique to prokaryotes. • 3Photoheterotrophs - light to generate ATP, obtain carbon in organic form. • Restricted to prokaryotes. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://www.theguardians.com/Microbiology/lyngb3_bg.jpg QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. • 4Chemoheterotrophs must consume organic molecules for energy and carbon. • Found in prokaryotes, protists, fungi, animals, and even some parasitic plants. • Majority of prokaryotes chemoheterotrophs. • Include saprobes (decomposers) and parasites. QuickTime™ and a dec ompres sor are needed to s ee this pic ture. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings • O2 also has impact. • Obligate aerobes require O2 for respiration. • Facultative anerobes will use O2 if present; can also grow by fermentation in anaerobic environment. • Obligate anaerobes are poisoned by O2 use either fermentation or anaerobic respiration. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture . QuickTime™ and a decompressor are needed to see this picture. http://www.medschool.lsuhsc.edu/microbiology/DMIP/cpgs.jpg • 1st prokaryotes - heterotrophic - fed on primordial soup - depleted supply of organic molecules in environment. • Natural selection favored prokaryote that could harness energy of sunlight make ATP. • Photosynthesis probably evolved once and was lost by heterotrophs. QuickTime™ and a d eco mpres sor are nee ded to s ee this picture. http://www.multihostingservice.co.uk/teamanarchy/simo n/images/Sporesom4.jpg QuickTime™ and a decompressor are needed to see this picture. • Atmosphere transformed from reducing one to oxidizing one by evolution of cyanobacteria. • Cellular respiration probably evolved by modification of photosynthetic equipment for new function (both use electron transport chain). Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://www.mfe.govt.nz/publications/ser/snapshot-lakewater-quality-nov06/html/images/cyanobacteria.jpg QuickTime™ and a decompressor are needed to see this picture. Survey of Prokaryotes • Archaea - extremophiles, “lovers” of extreme environments. • 1Methanogens - obtain energy by using CO2 to oxidize H2 replacing methane as waste - live in swamps and marshes, guts of animals. • May contribute to global warming. QuickTime™ and a decompressor are needed to see this pict ure. http://genome.jgi-psf.org/finished_microbes/images/metba.gif QuickTime™ and a decompressor are needed to see this picture. • 2Extreme halophiles - saline places - Great Salt Lake, Dead Sea. • Colonies form purple-red scum from photosynthetic pigment similar to pigment found in human retina. QuickTime™ and a decompressor are needed to see this picture. • 3Extreme thermophiles - hot environments - optimum temperatures for most - 60oC-80oC. • One sulfur-metabolizing thermophile lives at 105oC water near deep-sea hydrothermal vents. Quic kTime™ and a dec ompres sor are needed to see this pic ture. http://www.ls.toyaku.ac.jp/~lcb-7/images/hydrothermalvent.jpg QuickTime™ and a decompressor are needed to see this picture. Why important? QuickTi me™ and a decompressor are needed to see thi s pi ctur e. • Decomposers - important to nutrient recycling. • Nitrogen fixation - important to nitrogen cycle. • Many - symbiotic - involved in mutual relationship with host - i.e. fish provides bioluminescent bacteria under eye with organic materials uses flashlight to lure prey, signal potential mates. • Most of the time our defenses check growth of pathogens. • Pathogenic prokaryotes cause half of all human disease when internal defenses cannot fight them off. Quic kTime™ and a dec ompres sor are needed to see this pic ture. • Some pathogens - opportunistic (always in our system) - attack only when defenses down. • Robert Koch 1st to connect certain diseases to specific bacteria established Koch’s postulates. • Ensures that pathogen really is causing the disease. QuickTime™ and a decompressor are needed to see this picture. http://upload.wikimedia.org/wikipedia/commons/thumb/6 /67/Escherichia_Coli_NIAID.jpg/180pxEscherichia_Coli_NIAID.jpg QuickTime™ and a decompressor are needed to see this picture. • Pathogens can cause illness by producing poisons - exotoxins and endotoxins. • Exotoxins are proteins secreted by prokaryotes - can produce disease symptoms even if prokaryote not present. • Endotoxins - components of outer membranes of some gram-negative bacteria. • Common in food poisoning. Quic kTime™ and a dec ompres sor are needed to see this picture. • Disease control mostly due to education, not to expansion of drugs. • Overuse of antibiotics has led to evolution of new strains of bacteria. • Biological warfare also still a threat. • Humans use prokaryotes to treat biological issues, such as oil spills. QuickTime™ and a decompres sor are needed to s ee this picture.