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The most common fuel in organisms is __
glucose
Other molecules are first converted into glucose or other intermediate compounds.
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Glucose metabolism pathway traps the free energy in __
ATP
ADP + P + free energy > ATP
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Glucose oxidation is __
highly exergonic; drives endergonic formation of many ATP molecules
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If O2 is present (aerobic) glycolysis is followed by __
3 pathways of cellular respiration:
- pyruvate oxidation
- citric acid cycle
- electron transport chain
(page 9 on slide)
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If O2 is not present (anaerobic), pyruvate from glycolysis is metabolized by __
fermentation
(page 9 on slide)
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redox reaction
One substance transfers electrons to another substance
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gain of one or more electrons by an atom, ion, or molecule
reduction
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loss of one or more electrons. also occurs if H+ are gained or lost (H = H+ + e-)
oxidation
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In glucose combustion, __ is the reducing agent, __ is the oxidizing agent.
glucose; O2
Energy in glucose is transferred to the reduced product.
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The most reduced state has the __ free energy while the most oxidized state has the __ free energy.
highest; lowest
(page 14 on slide)
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NAD+ is __. NADH is __
oxidized; reduced
NAD+ is a key electron carrier in redox reactions. NADH gains 2 e-
(page 17 on slide)
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metabolic pathways that occur outside the mitochondria
- glycolysis (in cytosol)
- fermentation
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metabolic pathways that occur inside the mitochondria
- citric acid cycle
- pyruvate oxidation
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Cellular respiration reactions occur in the __
cristae of the mitochondria
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Glycolysis converts __ to __ & generates no __
glucose; pyruvate; CO2
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Glycolysis involves __ enzyme-catalyzed reactions.
10
- energy-investing: 1-5 require ATP
- energy-harvesting: 6-10 yield NADH & ATP
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Glycolysis results in __
- 2 molecules of pyruvate (3-carbon)
- 2 molecules of ATP
- 2 molecules of NADH
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active sites of hexokinase
glucose & ATP
(Hexokinase is the substrate.)
(page 27 on slide)
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What happens during the reaction with hexokinase?
- phosphorylation (addition of phosphate group) & loss of ATP
- G6P (glucose derivative) is produced with that extra phosphate.
(page 27 on slide)
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active sites of phosphofructokinase
F6P (glucose derivative) & ATP
(Phosphofructokinase is the substrate.)
(page 28 on slide)
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What happens during the reaction with phosphofructokinase?
- Phosphofructokinase adds a 2nd kinase.
- Another phosphate group derived from ATP is attached to F6P (glucose derivative) - phosphorylation reaction
(page 28 on slide)
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What does aldolase do and produce?
opens the carbon ring (6-carbon) & cleaves it producing TWO 3-carbon sugar molecules (3GP) - electron rich
1 6-carbon splits into two 3-carbons.
(One of the 3GP is modified from DAP)
(page 30 on slide)
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key concepts during the first steps in the energy-harvesting (releasing) reaction of glycolysis
- 1st drop in free energy
- redox reaction
- substrate phosphorylation
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What happens during the first steps in the energy-harvesting (releasing) reaction of glycolysis?
- Each G3P will lose 2 electrons, resulting in a total of 4 electrons lost (redox reaction)
- 1 phosphate added per molecule, producing a total of 2 ATP (substrate-level phosphorylation)
(page 32 on slide)
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substrate-level phosphorylation
transferring a phosphate group from a substrate (glucose derivative) to ADP to form ATP
(Each ATP molecule produced in the energy-releasing steps of glycolysis results from substrate-level phosphorylation).
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__catalyzes formation of __ & __, the final product of glycolysis.
- Pyruvate kinase;
- ATP (by substrate-level phosphorylation);
- pyruvate
(page 35 on slide)
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