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51 Cards in this Set
- Front
- Back
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Life Is Work |
Life Is Work |
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Living cells Require |
transfusions of energy from outsidesources to perform their many tasks |
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Energy |
Flows into anecosystem assunlight andleaves as heat -The giant panda– Obtains energy for its cells by eating plants |
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exergonic reaction |
The breakdown of organic molecules that posses potential energy -fuel |
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Catabolic pathways yield |
energy by oxidizingorganic fuels -& Due to the transfer of electrons |
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Cellular respiration |
- Is the most prevalent and efficientcatabolic pathway – Consumes oxygen and organic moleculessuch as glucose -Produces CO2, – Yields ATP – Keeps cells working by regenerating ATP -aerobic & anaerobic processes -Occurs in a stepwise fashion. If it didn’t,there would be explosions when you eat! -Oxidizes glucose in a series of steps |
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Redox reactions |
Transfer electrons from one reactant toanother by oxidation and reduction |
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oxidation |
-A substance loses electrons, or is oxidized -ends up more + -(Oxidation Is Loss) OIL |
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reduction |
-A substance gains electrons, or is reduced -(ends up more – ) -(Reduction Is Gain) RIG |
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Electrons are transferred to more |
electronegative atoms. The formation of amore stable arrangement releases energy. |
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Electronegativity |
is a measure of the tendency of an atom to attract a bonding pair of electrons. >^ -pull for electrons |
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Some redox reactions |
-Do not completely exchange electrons -Change the degree of electron sharing incovalent bonds |
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cellular respiration redox |
Glucose is oxidized and oxygen is reduced |
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If electron transfer is not stepwise (CR) |
-A large release of energy occurs -As in the reaction of hydrogen and oxygento form water |
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NAD+ |
-nicotinamide adenine dinucleotide, a derivative of the vitamin niacon - an electron carrier (acceptor), a coenzyme - hydrogens atoms pass through here first - can cycle easily between oxidized (NAD+) and reduced (NADH) states |
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NADH |
-the reduced form of NAD+ -Passes the electrons to the electrontransport chain (acts as electron shuttle) |
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The electron transport chain (ETC) |
-Passes electrons in a series of steps insteadof in one explosive reaction -Uses the energy from the electron transferto form ATP - O2 captures electron forming water -NADH-O2= exergonic reaction -Electrons from NADH and FADH2 loseenergy in several steps |
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Dehydrogenase |
enzyme, NAD+=NADH |
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Respiration three metabolic stages: |
1. Glycolysis 2. The citric acid cycle 3. Oxidative phosphorylation |
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1. Glycolysis |
-Breaks down glucose into two molecules ofpyruvate -harvests energy by oxidizing glucose to pyruvate – Means “splitting of sugar” (glyco lysis) – Breaks down glucose into pyruvate -Occurs in the cytoplasm (cytosol) of the cell |
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2. The citric acid cycle |
-Completes the breakdown of glucose -The citric acid cycle completes the energy yieldingoxidation of organic molecules -Takes place in the matrix of the mitochondrion -The remaining 2 carbonatoms attached to CoAenter the citric acidcycle and are completelyoxidized to CO2 -Energy from theseoxidizations is capturedon the e- carriers NADHand FADH2 - |
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3. Oxidative phosphorylation |
Is driven by the electron transport chain Generates ATP |
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substrate-levelphosphorylation |
-a mode of ATP synthesis occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP -Both glycolysis and the citric acid cycle can generate ATP by this |
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Glycolysis consists of twomajor phases |
1. Energy investment phase 2. Energy payoff phase |
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Energy investment phase |
-2 ATP used -2ADP+2P -1-5 |
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Energy payoff phase |
- 4 ADP + 4 P, 2 NAD+ + 4 e- + 4 H +, used - 4 ATP, 2 NADH + 2 H+, formed, -2 Pyruvate + 2 H2O result of all - 6-10 |
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Energy Payoff Phase yields: |
2 NADH 2 H+ 4 ATP 2 H2O 2 Pyruvate (per glucose) |
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converted to acetylCoA |
-Before it can begin Pyruvate must first be converted to acetyl CoA, which links the cycle to glycolysis - 1-3 - co2 leaves -NAD-NADH -Coenzyme A enters |
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whatgoes into thecitric acid cycleand what comesout. |
in: NADH Purvate/CoA out: 3 NADH 1 FADH2 1 ATP 2 CO2 |
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oxidative phosphorylation |
NADH and FADH2 donate electrons to the electron transportchain, which powers ATP synthesis via • Electrons in NADH and FADH2 arecarrying energy to the ETC |
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Chemiosmosis |
-Is an energy-coupling mechanism that usesenergy in the form of a H+ gradient across amembrane to drive cellular work -During oxidative phosphorylation, couples the process ofelectron transport to ATP synthesis |
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ETC via Citrus Cycle |
-In the electron transport chain– Electrons from NADH and FADH2 loseenergy in several steps -At the end of thechain– Electrons are passedto oxygen, formingwater |
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H+ gradient |
– Stores energy – Is referred to as a proton-motive force – Drives chemiosmosis in ATP synthase |
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At certain steps along the electron transportchain |
Electron transfer causes protein complexesto pump H+ from the mitochondrial matrixinto the intermembrane space |
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ATP synthase |
Is the enzyme that actually makes ATP |
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During respiration |
most energy flows in thissequence: – Glucose to NADH to electron transportchain to proton-motive force to ATP |
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About 40% of the energy in a glucose molecule |
Is transferred to ATP during cellularrespiration, making approximately 32 ATP -• Only about 15-20% of the energy in gasolineis converted to mechanical force in a car |
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Fermentation |
-One catabolic process, Is a partial degradation of sugars thatoccurs without oxygen • Fermentation enables some cells to produceATP without the use of oxygen |
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Glycolysis FER |
– Can produce ATP with or without oxygen, inaerobic or anaerobic conditions – Couples with fermentation to produce ATP |
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Fermentation consists of |
Glycolysis plus other reactions thatregenerate NAD+, which can be reused byglycolysis |
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alcohol fermentation |
Pyruvate is converted to ethanol in twosteps, one of which releases CO2 -2 Pyruvate -2 Acetaldehyde -Ethonal |
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lactic acid fermentation |
Pyruvate is reduced directly to NADH toform lactate as a waste product |
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Both fermentation and cellular respiration |
– Use glycolysis to oxidize glucose and otherorganic fuels to pyruvate – Differ in their final electron acceptor -Cellular respiration produces much more ATP -Pyruvate is a key juncture in catabolism |
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The Evolutionary Significance of Glycolysis |
– Occurs in nearly all organisms – Probably evolved in ancient prokaryotesbefore there was oxygen in the atmosphere -Glycolysis and the citric acid cycle connect tomany other metabolic pathways… |
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The Versatility of Catabolism |
Catabolic pathways– Funnel electrons from many kinds of organicmolecules into cellular respiration -The catabolism ofvarious moleculesfrom food |
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Biosynthesis (Anabolic Pathways) |
-The body uses small molecules to build othersubstances -These small molecules May come directly from food, or throughglycolysis or the citric acid cycle |
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Regulation of Cellular Respiration viaFeedback Mechanisms |
Cellular respiration Is controlled by allosteric enzymes at keypoints in glycolysis and the citric acid cycle |
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Inhibitors occur when |
theres enough ATP or Citrate, then inhibits Phosphofructokinase by blocking AMP |
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Glycolysis in&out |
in: Glucose out: 2 Pyruvate 2 ATP 2 NADH |
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Citricacidcycle in&out |
in: 2 Pyruvate 2 Acetyl CoA2 Oxaloacetate out: 2ATP 8 NADH 6 CO2 2 FADH2 |
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oxidativephosphorylation in&out |
-inputs areelectrons from NADH andFADH2, and oxygen as theterminal electron acceptor. -Outputs are reducedoxygen (water) and aproton gradient across theinner mitochondrialmembrane, which is used todrive the synthesis of ATP. |
