Chapter 27 Prokaryotes 1 Structure a Most are unicellular some are colonial and even multicellular b Shape 3 main types i Cocci spheres ii Bacilli rods iii Spirilja helices c Diameter most 1 5 um most eukaryotes are 10 100 um d Cell walls i Protein sugar Peptidoglycan ii Maintains shape physical protection prevents cell from bursting 2 Gram stain taxonomic tool differentiates cell wall a Domain Bacteria i Gram positive simpler cell walls lots of peptidoglycan ii Gram positive bacteria peptidoglycan traps crystal violet 1 Gram negative a More complex often more resistant to antibiotics b More threatening to humans c d Crystal violet is often rinsed away revealing red dye Lipopolysaccharides in wall often toxic iii Antibiotics penicillin and others 1 Prevent the synthesis of cross links in peptidoglycan prevent bacteria from making new cell wall 2 Eukaryotes do not synthesize peptidoglycans i Sticky layer around cell wall adhesion to substrate or other bacterial cells may increase resistance to host defenses ii Fimbrae allows cell to adhere to substrate 1 Neisseria gonorrhoeae uses them to attach to mucous membrane of 3 Capsule 4 Motility about half are capable of taxis host causes gonorrhea a Taxis directed movement towards or away from a stimulus photo chemotaxis b Speed 50 um sec 100 body length sec i Size so small like you swimming in molasses Flagella 1 10 diameter of Eukaryotic flagella not covered by extension of plasma Lack true nuclei Lack compartmentalization by internal membranes i In folded membrane of a prokaryote for use in respiration mitochondria of eukaryotic cell 5 Cellular Structure c a b c Genome i Smaller 1 1000 the DNA of eukaryotes ii One double stranded ring not linear iii Little protein associated with it iv Plasmids smaller rings of DNA 1 Most with a few genes 2 Give the organism additional characters 3 Resistance to antibiotics 4 Ability to synthesize nutrients 5 Replicate independently of the genome transferred during conjugation d Reproduction i Mainly asexually cell division by binary fission not mitosis or meiosis ii Generation time short 20 minutes hours can adapt quickly to the environment typically 1 3 hours iii Population growth is geometric 1 Doubling with each generation 2 Depends on environmental conditions such as pH temperature and salinity iv growth in prokaryotes typically refers to population increases increase of number of cells rather than enlargement of individual cells 1 A single cell can produce a colony e Endospore cell that is resistant to extreme heat cold poisons dehydration Outer cell may disintegrate i autoclave required for sterilization f Conjugation genetic material is transferred between prokaryotic cells i DNA transfer is one way in bacteria donor cell and recipient cell ii Donor cell with F factor produces a pilus connection to recipient cell iii F factor a piece of DNA required for the production of pili 1 F factor may be part of the chromosome or part of a plasmid g Transformation a prokaryotic cell takes up and incorporates exogenous DNA from the surrounding environment 6 Nutrition how organisms receive energy and carbon a Photoautotrophs prokaryotes algae plants use light for energy get carbon for CO2 b Chemoautotrophs prokaryotes energy by oxidizing inorganic chemicals H2S ammonia iron carbon from CO2 c Photoheterotrophs i Use light energy for ATP ii Need organic source of carbon glucose iii Only certain prokaryotes d Chemoheterotrophs i Need organic molecules for energy and carbon prokaryotes protists fungi animals some plants 7 Oxygen 8 Phylogeny obligate aerobe uses 02 for cellular respiration a b Facultative anaerobe uses O2 if present but can respire anaerobically c Obligate anaerobes poisoned by O2 a Differences 2 domains Archaea as different from Bacteria as they are from Eukarya 9 Domain Archaea a Inhabit extreme environments 3 main types i Methanogens have a unique mode of nutrition 1 Uses H2 to reduce CO2 to CH4 2 Obligate anaerobes 3 Habitats swamps marshes where other microbes have depleted the O2 guts of herbivorous animals cattle used in sewage treatment ii Extreme halophiles live in very saline environments 1 Great salt lake dead sea saline ponds 15 20 salts seawater is 3 salts 2 Purple red color Celsius iii Extreme thermophiles live in very hot environments optimum 60 80 degrees 1 Hot sulfur springs hydrothermal vents 2 Thought to be the closest relatives to Eukaryotic cells iv Extreme halophiles 1 Purple red scum from photosynthetic pigment bacteriorhodopsin 2 Similar to the visual pigment in the human retina v Thermophiles 1 Yellowstone hot springs hydrothermal vents 10 Domain Bacteria most prokaryotes a Molecular methods used to draw phylogenetic relationships 11 Ecological Impacts of Prokaryotes a Chemical cyclins i Decomposers exchange between dead organisms and soil ii Carbon nitrogen phosphorous exchange between atmosphere and organic nutrient pool iii Fix CO2 nitrogen b Symbiotic associations in each case bacterium benefits i Commensalism host not harmed ii Parasitism bacteria harms the host such as disease iii Mutualism host benefits 1 Legumes have bacteria living in nodules prokaryotes fix nitrogen from N2 NO3 2 Flashlight fish light comes from mutualistic bioluminescent bacteria c Disease illness caused by pathogenic prokaryotes i Opportunistic prokaryotes Streptococcus pneumonia 1 Lives in throat of healthy adults when host is weakened they can multiply causes pneumonia 2 Haemophilus influenza bacteria that can cause pneumonia ii How do they harm us 1 Do damage with growth a Exotoxins more common proteins secreted by prokaryotes toxin from growth of Clostridium botulinum grows anaerobically in improperly canned foods causes botulism deadly b Endotoxins components of outer membranes of some gram negative bacteria Salmonella 2 lyme disease is caused by a spirochete can be cured if antibiotics are administered within a month after exposure 12 Important uses a Antibiotics half come from soil bacteria Streptomyces streptomycin erythromycin tetracycline b Food processing milk to yogurt and cheese c Culture drugs and vitamins d Waste treatment sewage pesticides petroleum e Produce biofuels 13 Bioremediation use of organisms do remove pollutants from air water and soil