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Providence Journal Friday October 2, 2009
The New Yorker 3/20/1995 by Mort Gerberg
Figure 28-1 Page 567 BacteriaEukaryaArchaea Common ancestor of all species living today 3 Domains A common ancestor Characteristics plasma membrane cell walls DNA/RNA molecules ribosomes endosymbiosis
Figure Page 577 BacteriaArchaeaEukarya According to morphological similarities, prokaryotes should be closely related This view is incorrect!
Figure Page 578 Size varies Shape varies Mobility varies Small Large Compare relative sizes A wide variety of bacteria and archaea use flagella (left) to power swimming movements. These cyanobacterial cells (right) move by gliding across a substrate. The shapes of bacteria and archaea vary from rods such as Bacillus anthracis (left) and spheres to filaments or spirals such as Rhodospirillum. In some species, such as Streptococcus faecalis (right), cells attach to one another and form chains. The sizes of bacteria and archaea vary. Mycoplasma cells (left) are about 0.5 µm in diameter, while Thiomargarita namibiensis cells (right) are about 150 µm in diameter.
Biology: life study of What is Life? Cellular Structure: the unit of life, one or many Growth: cell enlargement, cell number Evolution: long term adaptation Behavior: short term response to stimuli Reproduction: avoid extinction at death Metabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation – processing materials and energy Movement: intracellular, movement, locomotion Properties of Life
Homeostasis - metabolism All of these nutritional modes are found among prokaryotes! Eukaryotes are not as diverse in their nutritional modes. Nutrition ModeEnergy SourceCarbon Source PhotoautotrophLightCO 2 ChemoautotrophInorganic chemCO 2 PhotoheterotrophLightOrganic chem Chemoheterotroph Organic chem
Photoautotrophs - photosynthesis Ancient pathway, but not universal Cyanobacteria, Algae, Plants light CO 2 + H 2 O O 2 + CH 2 O chlorophyll Purple-sulfur bacteria light CO 2 + H 2 S S 2 + CH 2 O chlorophyll
Cyanobacterial Vegetative Cell cell wall cell membrane lipid droplet nucleoid polyhedral body cyanophycin thylakoids cyanophycean starch vacuole polyphosphate granule mesosome light reactions cytosol Calvin cycle and starch synthesis photosynthesis product RubisCO crystals! Prokaryotes do not have chloroplasts… they became chloroplasts!
In a light microscope image: Thylakoids would not be visible, so green color would appear throughout cytosol with the nucleoid region lighter in color. Artificial coloration of TEM image But thylakoids shown as green would be natural! The location of bacteriochlorophyll! For the light reactions… searchutex/photogallery/Ana baena_cylindrica_629.htm
Figure 28.5 Page 572
Chemoautotrophs - N metabolism Cyanobacteria, Rhizobium - N 2 fixation H + + ATP + N 2 NH 4 + Nitrosomonas - nitrification (forms nitrite) 2 CO 2 + NH 4 + NO CH 2 O Pseudomonas - denitrification 2 CH 2 O + 2 NO 2 - N CO H 2 O Which of these processes is demonstrating chemoautotrophism?
Nitrosomonas - internal membranes use NH 4 + electrons in an ETS to produce ATP ATP and protons used to reduce CO 2 to CH 2 O
Rhizobium needs anaerobic conditions to convert N 2 into NH 4 + Legumes produce heme based molecules and rapid respiration to eliminate oxygen from root nodules that house the bacterium symbiosis. O=O NN Chemical similarity between these two molecules results in competitive inhibition of nitrogen fixation by oxygen.
Photoheterotrophs - strange Bacteria: Rhodospirillum, Rhodomicrobium Light C 2 H 4 O CH 2 O spirilloxanthin
Chemoheterotrophs - common! Escherichia coli and most eukaryotes…even plants! CH 2 O + O 2 CO 2 + H 2 O + ATP Carbohydrate, etc. provides both the energy source and the carbon source What is another chemoheterotrophic organism? Give the complete Latin binomial!
Chemoheterotrophy Aerobic Respiration –Glycolysis carbohydrate to pyruvate (in cytosol!) –Citric Acid Cycle pyruvate to carbon dioxide (in cytosol or matrix) –Electron Transport and Oxidative Phosphorylation (in mesosomes or cristae) CH 2 O + O 2 CO 2 + H 2 O Anaerobic Fermentation –Glycolysis to pyruvate (in cytosol) –Fermentive step(s) to return NAD + to glycolysis (in cytosol) C 6 H 12 O 6 C 3 H 3 O 3 - C 2 H 5 OH + CO 2 C 6 H 12 O 6 C 3 H 3 O 3 - H 3 CCHOHCOO - Notice how fermentation can produce gas or acids… These are just a few of the fermentive possibilities!
Cyanobacterial Vegetative Cell cell wall cell membrane lipid droplet nucleoid polyhedral body cyanophycin thylakoids cyanophycean starch vacuole polyphosphate granule mesosome electron transport sytem and oxidative phosphorylation cytosol glycolysis and Krebs cycle fuel for repiration I thought these were only photosynthetic?? Prokaryotes do not have mitochondria… they became mitochondria! If its metabolism is facultative and the organism is in anaerobic conditions… fermentation steps
Archaea have Homeostasis Photoautotrophs use Calvin Cycle (Pyrococcus) Chemoautotroph use reverse TCA to fix CO 2 and sulfur transporters used drive ATP synthesis Chemoheterotroph citric acid cycle, fermentation Nutrition ModeEnergy SourceCarbon Source PhotoautotrophLightCO 2 ChemoautotrophInorganic chemCO 2 PhotoheterotrophLightOrganic chem ChemoheterotrophOrganic chem Facultative (can do both, but one better than another) and Obligate (strictly just one or the other) Anaerobes and Aerobes
Halobacterium NRC-1 Salt ponds where seawater is evaporating Figure Page 590 This red color is high population densities of Halobacterium salinarium!
halobacterium/halobacteria_1.jpg 3 chromosomes: Main chromosome 2,015 kb 191 kb replicon 366 kb replicon Replicons have critical genes for: DNA polymerase Transcription factors Mineral uptake (K, PO 4 ) Cell division The genome has many insertion sites for foreign genes How do the 3 chromosomes migrate properly in binary fission? Bacteriorhodopsin: Protein + retinal A max 280 UV, 570 green nm energy for proton transport and phosphorylation without photosynthesis! Halobacterium salinarium Aerobic Respiration Up to 5 M (25% NaCl)! Great Salt Lake, Utah Red Sea, Asia Minor
Alam/publications/PNAS96-ZHANG.pd Cytoplasm Periplasmic space Cell Membrane Retinal lsu.epfl.ch/sh/bR_full.pdf Bacteriorhodopsin absorbs green from the visible spectrum, so what color is the pigment? Hint: it reflects the other colors of the spectrum
Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Halobacterium demonstrating? Hint: Light for energy Chemicals for carbon
Methanococcus.jpeg Methanococcus jannischii Isolated from white smoker hydrothermal vent 2600m deep on the East Pacific Rise
Methanococcus jannischii Isolated from white smoker hydrothermal vent 2600m deep on the East Pacific Rise Methanogen Obligate anaerobe H 2 as energy source CO 2 as carbon source CH 4 as byproduct of metabolism Temperature: 50-86°C Other archaeon species found in cow rumen (first stomach) Cow belches 50 L of methane per day What does this electron micrograph tell you? …about cell shape? …about motility?
Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Methanococcus demonstrating? Hint: H 2 for energy CO 2 for carbon
Sulfolobus species Figure Page 589
Sulfolobus acidocaldarius 75°C Optimum Obligate aerobe pH 1 to 6 Oxidize Sulfur or can use Fe 2+ or MnO 4 2- as electron acceptors…uses glycolysis and TCA cycle (same path we have, but in a very different environment)
Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Sulfolobus demonstrating? Hint: Organic chemicals for energy Organic chemicals for carbon
How do Archaea tolerate the heat? Proteins stabilized by more ionic bridges between amino acid r-groups and more-hydrophobic core amino acids Heat shock protein (chaperonins) refold denatured proteins…Pyrococcus 121°C for 1 hour! DNA depurination reduced by presence of 2,3- diphosphoglycerate. DNA supercoiling by reverse gyrase reduces denaturation Sac7d in Sulfolobus is a minor groove protein increases the DNA melting temperature by 40°C Histone-like proteins help stabilize DNA as well Heat-resistant di-bi-phytanyl diether lipid membranes (monolayer) prevent delamination of membrane
Cell Membrane Structure O O O O R R O O O O R R Composed of diglycerides R group may be phosphate, sulfate, or sugar Long chain branched hydrocarbon (not fatty acid) Hydrocarbons may be C20 or C40 If C20, the membrane is a bilayer: If C40, the membrane is a monolayer: In some species, the membrane is a mixture of both C20 and C40 diglycerides forming a mixed mono-/bi-layer. The C40 diglycerides prevent the bi-layer from de-laminating!
ag_franceschi/franceschi-projects-30S.html Not all thermophiles are archaeons! Thermus aquaticus Gram negative eubacterium Thermophile isolated from Yellowstone Hot Spring Optimum temperature 85°C Stability of macromolecules excellent Enzymes for research or commercial use Taq polymerase is the enzyme of PCR (Polymerase Chain Reaction) Lives near cyanobacteria which produce CH 2 O to feed Thermus
Photoautotrophism Photoheterotrophism Chemoautotrophism Chemoheterotrophism Which of these metabolic pathways is Thermus demonstrating? Hint: Organic chemicals for energy Organic chemicals for carbon
Yellowstone National Park Paint Pot Thermophilic cyano- bacteria and eubacteria form a natural community of producers and consumers.
Yellowstone National Park Paint Pot Thermophilic cyanobacteria and eubacteria form a natural community of producers and consumers. AAAAHM/b3hXvyjQA6o/IMG_0663.JPG
BacteriaArchaeaEukarya According to morphological similarities, prokaryotes should be closely related