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Microbio Exam 2
| Question | Answer |
|---|---|
| In photosynthesis, where do electrons for the reduction of CO2 come from | NADH or NADPH |
| Anoxygenic vs oxygenic photosynthesis | In anoxygenic photosynthesis, reducing power comes from sulfur(H2S), while in oxygenic photosynthesis, reducing power comes from H20, leading to hydrolysis of water to make oxygen |
| ____ chlorophyll molecules harvest light energy and transfer it on to ____ chlorophylls | Antenna, reaction center |
| Chloroplast | Only in euks, the organelle photosynthesis is associated with. Otherwise in proks, photosynthetic pigments are integrated into internal membrane systems |
| Within a photosynthetic membrane, chlorophyll or bacteriochlorophyll molecules are associated with proteins to form complexes consisting of __ to __ molecules | 50 to 300 |
| Chlorosome | Efficeint in low-light, present in green sulfur bacteria. |
| ____ and ____ are accessory pigments that absorb light and transge energy to the reaction center chlorophyll, thus ___ | Carotenoids and phycobilins, broaden the wavelengths of light usable in photosynthesis |
| Carotenoids also play a role in | preventing photooxidative damage to cells |
| Phycocyanin is a typical ___ | phycobilin |
| Where is phycocyanin located | Outside the thylakoid membrane, as allophycocyanin binds a transmembrane protein, and alspo binds phycocyanin |
| Purple phototrophic bacteria undergo which type of photosynthesis | Anoxygenic photosynthesis |
| The production of ATP in phyosynthesis is called | photophosphorylation |
| In anoxygenic photosynthesis, reducing power for CO2 fixation comes from ___ and requires ____ in purple phototrophs | Reducatnts in the environment, reverse electron transport |
| Anoxygenic photosynthesis has ___, while oxygenic has ___ photosystems | 1,2 |
| Reverse electron flow is used to generate | NADH/NADPH |
| In oxygenic photosynthesis, __ donates electrons to drive autotrpohy, and ___ is produced as a by-product | Water, oxygen |
| Photosystem II in ___ splits ___ to yield ___ | Oxygenic photosynthesis, H20, O2 |
| Most autotrophs(including phototrophs) accomplish CO2 fixation via ______, in which ___ plays a key role | Calvin cycle, RubisCO |
| What does RubisCO do | It joins CO2 into Ribulose bisphosphate, producing two PGAs(phosphoglyceric acids) RubisCO(Ribulose bisphosphate carboxylase) |
| Overall stoichiometry of the Calvin cycle | 6 CO2 + 12 NADPH + 18 ATP --> F6P + 12 NADP+ + 18 ADP + 17 Pi |
| Green sulfur bacteria bacteria use the ___ pathway for CO2 fixation, while green nonsulfur bacteria use the ____ pathway | reverse citric acid pathway hydroxypropionate pathway |
| Net reaction of the reverse citric acid pathway | 3 CO2 + 12 H + 5 ATP --> triose-P |
| Net reaction of hte hydroxypropionate pathway | 2 CO2 + 6 H + 3 ATP --> glyoxylate |
| Some chemolithotrophs are ____, meaning that | mixotrophic, although they are able to obtain energy from the oxidation of inorganic compounds, they require an organic carbon source |
| Hydrogen bacteria(what do they oxidize to produce what, and what carbon classes do they fall under) | Oxidize H2 compounds to generate a PMF and ATP synthesis. They are chemolithotrophs that are also autotrophs |
| Hydrogen bacteria fix CO2 via | the Calvin cycle |
| Sulfur bacteria oxidize __, belong to which carbon classes, and fix CO2 via | Reduced sulfur compounds(H2S, S(zero)), they are chemolithotrophs and autotrophs and use the Calvin cycle to fix CO2 |
| ___ is the most widely used electron acceptor in energy-yielding metabolism | Oxygen |
| Anaerobic respiration | Other compounds besides oxygen are used as electron acceptors. This is less energy efficient, but doesn't require the presence of oxygen |
| Assimilative vs dissimilative metabolism | Both are redutive processes In assimilative metabolism, compounds are used for biosynthesis In dissimilative metabolism, compounds(like CO2, sulfate, nitrate) are used as electron acceptors in energy metabollism |
| Many bacteria that use nitrate in anaerobic respiration use enzymes like ___ to eventually produce __ in a process called ___ | nitrate reducatase, N2 gas, denitrification |
| What are the steps in the dissimilative reduction of nitrate | Nitrate->nitrite->NO(gas)->N2O[nitrous oxide](gas)->N2(gas) The gases are released into the atmosphere in denitrification |
| the sulfate-reducing bacteria reduce __ to __ | Sulfate, hydrogen sulfide |
| Two forms of active sulfate | APS(adenosine 5'-phosphosulfate) used in dissimilative metabolism, and PAPS(phosphoadenosine 5'-phosphosulfate) used in assimilative metabolism |
| In dissimilative sulfate reduction | reduced sulfate in the form of H2S is exreted |
| In assimlative sulfate reduction | Reduced sulfate is used in the synthesis of sulfur-containing organic compounds like methionine and cysteine |
| In the absence of an external electron acceptor, organic compounds can only be catabolized by | fermentation |
| For a compound to be fermentable, it usually needs to be able to form _____ that can yield ATP by __ | energy-rich organic intermediate, substrate-level phosphorylation |
| When pyruvate is broken down, the energy-rich intermediates formed are ___. __ is also produced, in order to ____. This second process is mediated by | Acetyl-CoA and Acetyl-P. H2 is produced in order to maintain electron(redox) balance. H2 is made by ferredoxin |
| Two examples of ATP synthesis without substrate-level phosphorylation or electron transfer | 1)Propionigenium modestum w/ succinate fermentation 2)Oxalobacter formigenes w/ oxalate fermentation In both cases, ATP synthesis occurs through the formation of proton gradients via Na+ and H+ |
| Syntrophy | Two organisms working together to degrade some compound that neither can degrade alone. Usually involves H2 made by one organism that is consumed by the other, allowing the H2 producer to make ATP |
| Example 1 of syntrophy | An ethanol fermenter produces acetate from ethanol with H2 as a sideproduct, which a methanogen uses to produce methane from CO2 |
| Example 2 of syntrophy | Butyrate is oxided to acetate, producing H2 which is consumed by a methanogen |
| Crotonate is oxidized into __ and reduced into __, generating a ___ | acetate, butyrate, PMF |
| Oxygenases | Introduce O2 into a compound |
| Two classes of oxygenases: What does each do | Dioxygenases: Incorporate both atoms of O2 into the molecule Monooxygenases: INcorporate only 1 oxygen atom of O2, and the second is reduced to water |
| Aerobic catabolysm of aliphatic and aromatic hydrocarbons involves | oxygenases |
| Anaerobic catabolism of aliphatic and aromatic hydrocarbons involves | Reductive(rather than oxidative) mechanisms of aromatic ring cleavage |
| Nitrogen fixation | The reduction of N2 to NH2 |
| What enzyme complex is required for nitrogen fixation? What does it consist of ? | Nitrogenase complex, consisting of dinitrogenase and dinitrogenase reductase |
| Most nitrogenases contain ___ or ___ plus __ as metal cofactors | Molybdenum or vanadium plus iron as metal cofactors |
| Overall reaction of the nitrogenase complex | 8 H+ + 8 e- + N2 -> 2 NH3 + H2, using 16-24 ATP |
| Nitrogenase and most associated regulatory proteins are encoded by __ | the nif regulon |
| Nitrogenase also reduces certain substances similar to N2, like | acetlene and cyanide |
| __ and __ suppress nitrogenase/nitrogen fixation | O2 and NH3 |
| Growth of most microorganisms occurs by | binary fission |
| Steps of binary fission | 1)DNA replication 2)Cell elongation 3)Septum formation 4)Completion of septum with formation of distinct cell walls 5)Cell separation |
| The __ proteins are key to cell division and chromosome replication | Fts proteins |
| Fts proteins interact to form a division apparatus in the cell called the | divisome |
| The protein ___ defines the vision plane in prokaroytes, forming a ___ | FtsZ, ring |
| Mre proteins | help define cell shape |
| How is new cell wall synthesized udring bacterial growth | By inserting new glycan units into preexisting wall |
| ___ can occur unless new cell wall precursors are spliced into existing peptidoglycan to prevent a breach in peptidoglycan integrity at the splice point | Autolysis |
| Bactoprenol | A hydrophobic alcohol that facilitates transport of new glycan units through the cytoplasmic membrane to become part of the growing cell wall |
| Precursors are bound to the peptidoglycan fabric in ___ | transpeptidation |
| Phases of the growth cycle | Lag phase, exponential phase, stationary phase(nutrient depletion or toxin buildup), death phase(occurs if you don't replenish nutrients) |
| Cell counts done microscopically measure | total number of cells in a population |
| Viable cell counts(plate counts) measure | only the living reproducing population |
| Three methods of plate counts | 1)Spread-plate method 2)Pour-plate method(medium is added after sample) 3)Serial dilutions |
| Why are plate count numbers lower than microscope counts | 1)The medium may prevent the growth of the microbe 2)Dead cells may be included in the microscopic count |
| Turbidity measurement requires | a standard curve |
| Batch culture | A closed system, in which there is a fixed volume of the medium that is altered by metabolic activities of the growing organissm |
| Continuous culture | An open system that also has a constant volume of medium, but with fresh medium added and spent medium removed continuously |
| What is a continuous culture device | Chemostat |
| In a chemostat, growth rate and yield can be controlled independently. How? | Growth rate is controlled by adjusting the dilution rate of the culture Growth yield is controlled by varying nutrient concentration |
| Dilution rate= | flow rate / volume of culture in the vessel |
| In a chemostat for a continuous culture, cell density(concentration) is controlled by | the level of limiting nutrient |
| The cardinal temperatures | the min, optimum, and max temperatures at which each organism grows |
| Why is there a min. growth temperature | Membrane gelling occurs, slowing transport processes |
| Mesophiles | have midrange temperature optima, and are found in warm-blodded animals and in temperate and tropical environemnts. |
| Psychrophiles | Live in cold environment, and have molecules that function best in the cold but that can be unusually sensitive to warmth |
| Organisms that grow at 0 degrees C. but have optima of 20-30 degrees C. are called | Psychrotolerant |
| Themophile growth optima | 45-80 degrees Celsius. Any greater is a hyperthermophile |
| Thermophiles and hyperthermophiles produce heat-stable macromolecules such as | Taq polymerase, used in PCR |
| Halophiles | Grow best at reduced water potential |
| Extreme halophiles | Require high levels of salt for growth |
| Under hypertonic conditions, a cell exists in an environment of __ water activity | Low(water leaves the cell) |
| Halotolerant organisms | Can tolerature some reduction in water activity, but generally grow best in the absence of the added solute |
| Xerophiles | Grow in dry environments |
| Compatible solutes | Maintain the cell in positive water balance to counteract increased solute concentration(which is a problem because it limits water activity) |
| __ can tolerate O2, but they don't use it | Aerotolerant anaerobes |
| __ use oxygen only when it is present in reduced levels | Microaerophiles |
| enzymes that neutralize toxic oxygen | Catalast, peroxidase, superoxide dismtase, superoxide reductase |
| Thioglycolate | A reducing agent used to test an organism's need for oxygen |
| Inhibition | Limiting microorganism growth, but not full sterilization |
| Dry heat destroys cells by | oxidation |
| Pasteurization | Does not sterilize, but reduces microbial load |
| Decimal reduction | The amount of radiation needed to reduce the number of the bacterial population 10-fold |
| Two radiation-resistant life forms | Viruses and endospores |
| UV radiation | Nonionizing, doesn't penetrate surfaces |
| Ionizing radiation | More power than UV radiation, and can pentrate objects |
| Which type of radiation is used for sterilization and decontaminiation | Ionizing radiation |
| Depth filter | Including HEPA filters, are used to remove microorganisms and other contaminants from liquid or air |
| Membrane filters | Used for sterilization of heat-sensitive liquids(.2 microns). Not small enough to work on viruses and bacterial mycoplasma |
| Nucleation filters | Used to isolate specimens for electron microscopy, when you want to observe microbes in a specimen |
| Cidal vs static | Cidal kills microbe, static inhibits growth |
| Bacteriocidal agents do not induce | lysis |
| MIC | Minimum inhibitory [], is the lowest concentration of the drug needed to prevent growth. It doesn't say if the drug is cidal or static |
| 3x used to disinfect nonliving materials | Sterliants, disinfectants, and sanitizers |
| Disinfection | The elimination of microbes from nonliving material |
| 2x used to reduce microbial growth on living tissues | Antiseptics and germicides |
| antimicrobial chemotherapeutic agents that inhibit cell wall synthesis | Cycloserine, vancomycin, bacitracin, penicillins, cephalosporins, monobactams, and carbapenems |
| antimicrobial chemotherapeutic agents that inhibit folic acid metabolism | Trimethroprim, sulfonamides |
| antimicrobial chemotherapeutic agents that inhibit cytoplasmic membrane structure | Polymyxins and daptomycin |
| antimicrobial chemotherapeutic agents that inhibit DNA gyrase | The quinolones(Nalidixic acid and ciprofloxacin) and nobobiocin |
| antimicrobial chemotherapeutic agents that inhibit RNA elongation | Actinomycin |
| antimicrobial chemotherapeutic agents that inhibit DNA-directed RNA polymerase | Rifampin and streptovaricins |
| antimicrobial chemotherapeutic agents that inhibit 50s(protein synthesis inhibitors) | Erythromycin(macrolides), chloramphenicol, clindamycin, and lincomycin |
| antimicrobial chemotherapeutic agents that inhibit 30s(protein synthesis inhibitors) | Tetracyclines, spectinomycin, streptomycin, gentamicin, kanamycin, amikacin, and nitrofurans |
| antimicrobial chemotherapeutic agents that inhibit tRNA(protein synthesis inhibitors) | Mupirocin and puromycin |
| ___ is a drug of last resort for VDRs(very drug resistant bacteria) | Vancomycin |
| ____ is used to treat TB, supplemented by __ | Rifampin, isoniazid, which inhibits mycolic acid synthesis for the mycobacteria tuberculosis that cause TB |
| Broad-spectrum antibiotics work on | both gram+ and - bacteria |
| Fusion inhibitors | Blocks fusion of virus with the host cell |
| Sulfa drugs, isoniazid, and nucleic acid analogs are examples of | growth factor analogs |
| Growth factor analogs are | synthetic metabolic inhibitors |
| Sulfanilamide is an analog of | PABA |
| The growth factor for phenylalanine is | p-Fluorophenylalanine |
| The growth factor for uracil is | 5-fluorouracil |
| The growth factor for thymine is | 5-bromouracil |
| PABA is a precursor for | folic acid, needed for metabolic processes in bacteria |
| Quinolones | inhibit the action of DNA gyrase in bacteria |
| Ciprofloxiacin is a __ used to treat __ | quinolone used to treat anthrax |
| Nucleoside analogs are aka __ and do what | NRTIs(Nucleoside reverse transcriptase inhibitors), they inhibit elongation of the viral nucleic acid chain by polymerase |
| Nevirapine | A NNRTI(non-nucleoside reverse transcriptase inhibitor that binds directly to reverse transcriptase and inhibits reverse transcription |
| Penicillin blocks ___ by blocking which process | peptidoglycan cell wall synthesis by blocking transpeptidation |
| Cephalosporins block ___, preventing the formation of ___ | They block the transport of glycan units into the membrane for the synthesis of peptidoglycan |
| The B-lactam antibiotics include | Cephalosporins and penicillins |
| B-lactamase inhibitors allow | B-lactam antibiotics like penicillin and cephalosporins to work longer |
| Many semisynthetic penicillins are effective against | gram - bacteria |
| 3x are strucurally complex molecules, produced by bacteria against other bacteria, and interfere with steps of ____ | aminoglycosides, macrolides, and tetracycline, all work by interfering with protein synthesis |
| An example of an aminoglycoside is | kanamycin |
| An example of a macrolide is | erythromycin |
| ____ is a fusion inhibitor composed of a 36-aa synethic peptide that binds the ___ membrane protein of HIV | enfuvirtide, gp41 |
| gp41 | Produced by HIV, induces fusion with the host cell(T lymphocytes) |
| Interferons | Induce proteins that inhibit viral replication |
| Neuraminidase inhibitors | Block the active site of influenza neuraminidase |
| NNRTI | Nonnucleoside reverse transcriptase inhibitors, a reverse transcriptase inhibitor |
| Nucleoside analogs | Inhibit viral polymerase, reverse transcriptase, and blocks capping of viral RNA |
| Nucleotide analogs | Block viral polymerase and reverse transcription |
| Synthetic amines | Block viral uncoating |
| Antifungal angents target | Ergosterol(relative of chloresterol in yeast),chitin(a long-chain polysaccharide of glucose that is the peptidoglycan of fungi), disruption of microtubule formation via griseofulvin |
| 5x mechanisms of drug resistance | 1)Destruction of the drug 2)Modify drug 3)Modify drug taget 4) Block entry/increase removal via pumping 5)Modify biochemical pathway |
| Photosystem 1 of oxygenic photosyntheis is | like photosystem I of anoxygenic bacteria |
| Photosystem 2 in oxygenic photosyntehsis | splits H20 to yeild H20 |
| RubisCo plays a big role in | fixation of C02 via the calvin cycle |
| Hydrogen bacteria fix CO2 via the | calvin cycle |
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