Term
Metabolism
-Biological
-Physilogical
-Ecolgical |
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Definition
–Biochemical: Function is determined by structure.
–Physiological: Life is sustained by the continual transduction of energy.
–Ecological: The flow of energy thru the biota is closely tied to the carbon cycle. |
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| Why do cells need energy ? |
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Definition
–to import nutrients from the environment against concentration gradients.
–to build complex molecules from simpler precursors, i.e. to grow and reproduce.
–for internal and environmental motion.Cilia and flagella |
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| Ultimate Source of Energy ? |
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Definition
| Sunlight. Few exceptions are is hydrothermal waves. |
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| Energy on ecosystem scale. |
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Definition
–aerobic respiration is the thermodynamic equivalent of anaerobic respiration + chemolithotrophy |
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| Ecosystem scale of energy transfer flow chart. |
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Definition
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| Redox Reactions Require ? |
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Definition
•reduction (redox) reactions require an electron donor and an electron acceptor.
– acceptor + electrons <===> donor |
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| How do you get energy from redox reactions? |
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Definition
–Molecules with high redox potentials oxidize molecules with lower redox potential, which yields energy. |
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Definition
•Consider these reactions:
–NAD+ + 2H+ + 2e- ==> NADH + H+ (E = -320 mv)
–1/2 O2 + 2H+ + 2e- ==> H2O (E = +820 mv)
•If O2 is used to oxidize NADH (this is what happens during aerobic respiration), the potential difference is 1140 mv.
•This potential across a membrane is what drives the phosphorylation of ADP by ATP synthase. |
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| Aerobic metabolism process. |
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Definition
| Take glucose then take NADH use NAD to oxidize glucose then O2 oxidizes NADH |
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Definition
| electron transport system still dumps electron on something like Iron, but get less membrane potential beucase only 700mv potential e.i dont get as much energy |
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| What happens to Fe 2+ after reduced ? |
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Definition
| Floats to aerobic environment that can be used by aerobies to dump electrons onto O2 to get energy from it |
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Definition
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| Energy aquestion in bacteria and archea |
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Definition
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How much energy is needed to make oxygenic photosynthesis work? |
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Definition
–1/2 O2 + 2H+ + 2e- ===> H20 (E = +820 mv)
–an energy input equivalent to 820 mv is needed to decompose water to feed electrons into photosynthesis.
–These electrons are captured by NADPH which is then oxidized to produce the energy (ATP) and H+ used to reduce CO2 to organic molecules. |
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Term
•Reduction of CO2 requires an additional energy input: |
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Definition
–CO2 + 4H+ +4e- ===> CH2O + H2O E= -430 mv
–Need a total input of solar energy of at least 1250 mv to reduce CO2 using electrons from H2O |
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Definition
| Respiration in reverse. Sunlight used to make ATP and crack water(photo 2) to get electrons to reduce NADP+ to NADPH(photo 1), which is used to fix CO2 |
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| Special thing about eukaryotes vs prokaryotes |
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Definition
| Compartmentalized reactions in mitochondria and chloroplast. All this happens in the same membrane for prokarotes. |
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Definition
Glycolysis is the same 6 carbons in 6 carbons out
The potential difference between NADH and O2 is as good as it gets for organisms.
–If you use a terminal electron acceptor other than O2 [such as NO3-, or SO4-- or Fe+++], i.e. anaerobic respiration, the energy yield is lower.
–For an anaerobe, this means either that you settle for life at a slower pace (lower growth rate) or you have to process a larger quantity of substrate to get an equivalent energy yield.
•transporting more substrate costs energy too. |
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Term
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Definition
•Enzymes – proteins, sometimes with prosthetic groups, that increase reaction rates by lowering activation energy.
–They do this by destabilizing existing bonds and stabilizing transition states.
•The kinetics of many enzymatic reactions, and many biochemical processes, including nutrient uptake and growth can be described by Michaelis-Menten model. |
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Definition
•Every handling system has a finite capacity.
–At low input rate, the system will process what it has available
•i.e. the rate of the reaction or process will be directly proportion the availability of substrate.
–As the system reaches its capacity, it will not respond to increases in substrate availability.
–The processing rate at full capacity (or saturation) is called Vmax. Max enzyme can pump out
–Processing capacity includes the capacity per enzyme times the total number of enzymes.
Km substrate concentration required by the enzyme to operate at half its maximum velocity |
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Definition
•The other parameter of the MM model is Km.
–Km is a half-saturation constant
•the substrate concentration at which the processing rate (V) is equal to 1/2 of Vmax.
–Km tells you what the affinity of the handling system is for the substrate.
•Low Km means high substrate affinity but also that the system will saturate a relatively low substrate concentration.
•Although the MM model is simple. Much of the physiology and ecology of microorganisms can be understood in its context.
– V = Vmax ([S]/Km + [S] ) |
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Definition
•Rates of enzymatic reactions increase about 2X for each 10 C rise in temperature.
•Cell membranes are also temperature sensitive: melt or freeze.
•DNA and proteins denature too.
•The range for microbial growth is –20 to 120 C.
•For extreme highs (>100 C) and lows (< 0 C), the key to growth is liquid water.
–Liquid water >100 C is found in high pressure environments, i.e. deep hydrothermal vents.
–Solutes and surfaces depress the freezing temperatures, allowing metabolism to continue.
•Upper temperature limit for eukaryotes is 60 C. The cells are too complex; lots of internal membranes to melt. |
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Definition
•Psychrophiles – optimal growth at low temp.
–most will grow at 0 C.
–90% of the ocean < 5 C.
–Some algae grow in snow.
–Membranes contain unsaturated fatty acids.
•Thermophiles – have heat stable enzymes and membranes.
–stability arises from more internal bonding to prevent denaturation.
–Membrane lipids contain long saturated fatty acids.
–Membranes of extreme thermophiles are rigid lipid monolayers with ether-linked phospholipids.
•Molecular phylogenies place thermophiles at the base of all three domains. |
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Definition
•grow best at low oxygen concentration |
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Definition
•UV and shorter wavelength radiation causes oxidative damage to cells.
–Microbes in strong uv environments often have pigments to absorb radiation.
–Also have effective DNA repair mechanisms.
–Aromatic compounds are strong absorbers of uv.
•Such compounds include purines and pyrimidines, amino acids like phenylalanine, tyrosine, trytophan; and flavenoids. |
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Definition
•The breakdown and oxidation of organic molecules to generate energy and intermediates for biosynthetic pathways. |
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Definition
–Hydrolysis or oxidative breakdown of macromolecules to form monomers.
•Takes energy to make the necessary enzymes
–Monomers enter catabolic pathways (e.g. glycolysis) to yield intermediary metabolites (pyruvate, acetyl CoA).
•May yield some NADH or ATP
–Intermediates enter the CAC cycle and are oxidized to CO2.
•electrons go to NADH then pass thru an ETS to oxygen or other electron acceptor. |
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Definition
•Electrons generated along a glycolytic, or analogous pathway, are dumped onto an end product of the the pathway.
–No respiratory electron transport chain.
–ATP generated by substrate level phosphorylation. |
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| All microbial groups have a ? |
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Definition
•glycolytic pathway.
–functions aerobically and anaerobicially. |
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Term
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Definition
| Alcoholic, Latic acid, Fromic acid, Propionate. |
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Definition
–Pyruvate decarboxylated to acetaldehyde, releasing CO2, acetaldehyde reduced to ethanol. |
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•Lactic acid fermentation: |
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Definition
–Pyruvate directly reduced to lactate. |
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Definition
–Pyruvate decomposed to formic acid and acetyl CoA. Acetyl CoA eventually yields acetate and ethanol. Formic acid decomposed to H2 and CO2 : a major source of H2 in anaerobic environments. |
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Definition
–Propionic acid bacteria decarboxylate pyruvate, feed the acetate into pathway similar to first half of TCA cycle: make oxaloacetate, reduce it to malate, then fumarate, then decarboxylate to propionate. |
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Term
In anaerobic environments, fermentation can yield as much useful energy (ATP) as anaerobic respiration pathways. |
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Definition
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Term
| Oxidative phosphorylation |
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Definition
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