Micro Lecture Exam II

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Micro Lecture Exam II
2014-02-18 18:55:48

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  1. Classification of Microorganisms
    • 1. Nutritional
    • 2. Temperature
    • 3. Gas (O2)
  2. Autotrophs
    • 1. Photoautotroph- photosynthesize
    • 2. Chemoautotroph- oxidize chemical compounds
  3. Photoautotrophs
    • microbes that photosynthesize (derive energy from light and transform it into chemical energy that could be used in cell metabolism)
    • ex: Green sulfur bacteria, cyanobacteria
  4. Chemotrophs
    • microbes that oxidize chemical compounds
    • neither sunlight nor organic nutrients
    • oxidize inorganic compounds such as hydrogen gas, Hydrogen sulfide, iron, sulfur to obtain the necessary  energy to produce their own organic compounds)
    • ex: 1. Methanogens 2. vent bacteria
  5. Chemoheterotroph
    • derive both carbon and energy from organic compound (aerobic respiration)
    • ex: 1. Saprobes 2. Parasites
  6. Temperature requirements (Optimal)
    Optimal- the small intermediate between the minimum and maximum which promotes the fastest rate of growth and metabolism
  7. Psychrophiles
    • optimum temp of 15oC, it is an obligate in respect to the cold and cannot grow above 20oC
    • -20o to 15o C
  8. Mesophiles
    • gtow at intermediate temperatures (include most pathogens)
    • 10o to 50o C
  9. Thermophiles
    • grow at temperatures higher than 45oC
    • 45o to 80o C
  10. Facilitative Psychrophiles
    • grow slowly at a lower temperature, but have an optimum temp above 20o C
    • concern- they can grow in refrigerated food and cause food borne illness
    • ex: 1. Staphylococcus aureus 2. Listeria monocytogenes
  11. Thermoduric microorganisms
    • can survice short exposure to high temperatures, but are normally mesophiles
    • can be contaminants of heated and pasteurized foods
    • ex: 1. Bacillus 2. Clostridium
  12. Clostridium botulism
    • spore forming anaerobe that commonly inhabits soil and water and occasionally, the intestianal tract of animals
    • factors in food processing that lead to botulism dependent on several factors
    • concern-- spores present on vegetables or meat at the time of gathering and are difficult to remove by washing alone
  13. 1. Obligate aerobe
    2. Obligate anaerobe
    3. Facultative anaerobe
    4. Aerotolerant anaerobe
    5. Microaerophiles
    6. Capnophiles
    • 1. Obligate aerobe- requires O2
    • 2. Obligate anaerobe- O2 kills them
    • 3. Facultative anaerobe- can grow with or without O2
    • 4. Aerotolerant anaerobe- resists O2
    • 5. Microaerophiles- 4-6% O2
    • 6. Capnophiles- 3-10% O2
  14. Defenses against oxygen
    • build up of singlet oxygen and the oxidation of membrane lipids and other molecules can damage and destroy a cell
    • Superoxide ion, peroxide, and hydroxyl radicals are other metabolic by products of oxygen
  15. Anaerobic Infections in large intestine
    • during abdominal surgery
    • traumatic injuries to include gas gangrene and tetanus
  16. Anaerobe infections (Clostridium tetani)
    • in soil and gastrointestinal tracts of animals
    • spores usually enter body through accidental puncture wounds, burns, the umbilicus, frostbite, and crushed body parts
  17. Growing anaerobes
    requires special media, methods of incubation, and handling chambers that exclude oxygen
  18. Clostrium
    • produces toxins that kill surrounding tissues, providing the bacterium with more nutrients and increasing the size of the anaerobic environment necessary for Clostrium to grow
    • pain, gas gangrene (blackening of the infect muscle, skin and production of bubbles that may break out with a frothy brownish fluid)
    • shock, kidney failure, and death can follow often withing a week of infection
  19. Capnophiles
    • 1. Neisseria
    • 2. Brucella
    • 3. Streptococcus pneumoniae
    • (3-10% CO2 incubation)
  20. Microaerophiles
    • 1. soil
    • 2. water or
    • 3. human body
    • (small amounts of O2) (not exposed to the atmosphere)
  21. Aerotolerant anaerobes
    • not harmed by O2--> alternative mechanisms for breaking down peroxidde and superoxide
    • ex: 1. Lactobacilli 2. Streptococci
    • use manganese ions or peroxidases to do this
  22. Metabolism of Microbes
    • 1. Anabolism
    • 2. Carabolism
  23. Anabolism
    • building complex organic molecules from simpler ones
  24. Catabolism
    breakdown of complex organic molecules into simpler ones
  25. Enzymes
    • protein compounds
    • catalysts (speed up chemical reactions)
    • only lower energy of activation (do not create reactions)
    • substrate specific
    • coded by a specific gene
    • affected by pH and temperature
    • shape determines function
    • provide active sites for substrates
    • many enzymes need cofactors or coenzymes to work effectively
  26. Cofactor and Coenzymes
    • cofactors- inorganic ions (Mg, Fe)
    • many enzymes need cofactors to work effectively
  27. Inhibition
    • EA ( enzyme active site) can be blocked by the presence of inhibitors
    • drug affecting inhibitors (Sulfa drugs):
    •  kill bacteria by working as competitive inhibitors of EA in the synthesis of folic acid from para-amino-benzoic acid (PABA)
  28. Competitive inhibition
    substance resembles normal substrate competes w/substrate for active site
  29. Feedback Inhibition
    • concentration of product at the end of a pathway blocks the action of a key enzyme
  30. Enzyme repression
    • stop further synthesis of an enzyme somewhere along its pathway
    • any process where it keeps an enzyme to be made
    • as the level of the end product of a pathway has been built to excess, the genetic apparatus responsible for replacing these enzymes is automatically repressed
  31. Enzyme Induction
    • Process that allow the enzyme to be made
    • enzymes appear when suitable substrates are present
    • induced by a substrate (a carbohydrate-note lactose)
  32. Cellular Respiration (Glycolysis)
    Glycolysis occurs in the CYTOPLASM both prokaryotes and eukaryotes
  33. Cellular Respiration (Krebs Cycle)
    • Krebs Cycle- cytoplasm of prokaryotes
    •                    mitochondria of eukaryotes
  34. Cellular Respiration (Electron Transport Chain ETC)
    • ETC- cell membrane of prokaryotes
    •         mitochondrial membrane of eukaryotes
  35. Energy Strategies in microorganisms
    • 1. Aerobic respiration
    • 2. Anarobic respiration
    • 3. Fermentation
  36. 1. Aerobic Respiration
    • 3 main cathabolic pathways:
    • 1. Glycolysis, 2. KC 3. ETC
    • uses O2 as the main electron acceptor at the end of the ETC
    • main energy pathway of strict aerobes and facilitative anaerobes
  37. Differences in ETC
    the lack of cytochromes, catalase, and peroxidases in anaerobes may limit their ability to process free oxygen and contributes to its toxic effect on them
  38. 2. Anaerobic respiration
    • in organisms that can utilize and O2 containing salt as the final electron acceptor in the ETC
    • ex: nitrate, nitrite, sulfates, or carbonates)
    • used by:
    • 1. Strict Anaerobess
    • 2. Facultative Anaerobes
    • 3. Microaerophiles
    • 4. Aerotolerant anaerobes
  39. 3. Fermentation
    • incomplete oxidation of glucose and other carbohydrates (limited ATP production)
    • main products of fermentation:
    • 1. Ethanol (alcoholic fermentation)
    • 2. Organic acids ( mixed acidic fermentation) lactic, propionic, butyric, formic, acetic acids
    • Anaerobic fermentation:
    • 1. Souring milk (Streptococcus, Lactobacillus)