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Do microbes create energy from nutrients?
- No energy is never created nor destroyed, only moved around.
- They extract energy that is already present in the bonds of the nutrients.
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What is a Oxidation-reduction (redox) reaction?
It is a reaction that salvages electrons (and the energy associated with them) released from the breaking of nutrient bonds.
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What is ATP?
How energy is banked.
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What happens in a Oxidation reaction?
Oxidation is the removal of electrons from a molecule, and is always coupled with a Reduction reaction.
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What happens in a reduction reaction?
Reduction is the gaining of electrons, and are always coupled with Oxidation.
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What is a dehydration reaction?
- This is the removal of hydrogen atoms.
- Biological oxidation reactions are often dehydration reactions.
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Catabolic reaction
NAD+ + 2H++2e- = NADH+H+
This is energy extracted in the form of electrons
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What is the high energy of the cell?
- ATP
- ATP has "high energy" or unstable bonds which allows the energy to be released quickly and easily
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What are the mechanisms of ATP generation?
- Substrate-level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
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What is substrate-level phosphorylation
Generation of ATP when a high energy phosphate is transferred directly to ADP from a phosphorylated substrate.
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What is Oxidative phosphorylation
Electrons are transferred from organic compunds through a series of electron carriers to O2 or other oxidized inorganic or organic molecules.
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What is photophosphorylation
This occurs in photosynthetic cells, the light causes chlorophyll to give up electrons
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How do microbes generate energy?
- By the oxidation of..
- Carbohydrates
- Proteins
- Fats
- Vitamins
- Minerals
- Water
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In what ways to microbes catabolise carbohydrates?
- Cellular respiration
- Fermentation
Both start with Glycolysis
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What are the components of cellular respiration?
- Glycolysis
- Intermediate step
- TCA cycle (Kreb's cycle)
- Electron Transport Chain
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What is Glycolysis?
Glucose is oxidized to pyruvic acid with ATP and NADH produced
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What is the Intermediate step?
Pyruvic acid is converted to acetyle-CoA with NADH produced
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What is the TCA/Kreb's cycle?
Acetyl CoA is oxidized to CO2 with ATP, NADH and HADH2 produced
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What is the electron transport chain
NADH and HADH2 are oxidized through a series of redox reactions and a considerable amount of ATP is produced
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How many steps are in glycolysis?
10 steps
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Phosphogluconate pathway
- Used simultaneously with glycolysis (several intermediates can reenter glycolysis)
- Breakdown of 5-carbon sugars(pentoses) as well as glucose
- Produces important intermediates in the synthesis of, Cucleic acids, glucose from Co2 and certian amino acids
- Produces NADPH for anabolic reaction
- Yealds only 1 atp per glucose
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Entner-Doudoroff pathway
- Bacteria can metabolize glucose without glycolysis or pentose phosphate pathway.
- Produces 2 NADPH and 1 ATP/glucose
- Used by obligate aerobes such as Pseudomonas Spp.
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What happens after glycolysis
- After glucose is broken down to pyruvic acid, it can be channeled into either Fermentaion or
- Cellular respiration.
- Aerobic respiration or anaerobic respiration
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What is arobic respiration
- Tricarboxylic acid (TCA) cycle
- Kreb's cycle or citric acid cycle
- A large amount of potential energy stored in acetyl CoA is released by a series of redox reactions that transfer electrons to the electron carrier coenzymes (NAD+ and FAD)
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Acetyl CoA
- Used in the intermediate step
- Pyruvic acid is converted to a 2-carbon compound (decarboxylation)
- The 2 carbon acetle group then combines with Coenzyme A through a high energy bond
- NAD+ is reduced to NADH
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Summary of Glycolysis
- Glucose is split and oxidized through a ten step pathway to two molecules of pyruvic acid
- Net gain of 2 ATP molecules, 4 from energy phase(by substrate level phosphorylation) mins 2 from preparatory phase
- 2 NADH molecules produced (will be used to make more ATP)
- Pyruvic acid can now undergo either Fermentation or respiration
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