Term
| three pathways of respiration |
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Definition
1. glycolysis
2. citric acid cycle
3. oxidative phosphorylation |
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Term
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Definition
| a partial degradation of sugars/organic fuel that occurs without the use of oxygen |
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Term
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Definition
| the most prevalent and efficient catabolic pathway, oxygen is consumed as a reactant in the degradation of organic fuel. carried out by most prokaryotic and eukaryotic organisms. |
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Term
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Definition
| harvests chemical energy without oxygen |
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Term
| basic formula of aerobic respiration |
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Definition
| organic compounds + oxygen ----> carbon dioxide + water + energy |
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Term
| how do the catabolic pathways that decompose glucose yield energy? |
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Definition
| the transfer of electrons during chemical reactions releases energy stored in organic molecules, which is ultimately used to synthesize ATP |
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Term
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Definition
a reaction involving the transfer of one or more electrons from one reactant to another.
Xe- + Y ---> X + Ye- |
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Term
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Definition
the loss of electrons from one substance to another. in this case Xe-
Xe- + Y ---> X + Ye- |
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Term
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Definition
the addition of electrons from one substance to another. in this case Y
Xe- + Y ---> X + Ye- |
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Term
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Definition
the electron donor. in this case Xe-
Xe- + Y ---> X + Ye- |
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Term
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Definition
the electron acceptor. in this case Y
Xe- + Y ---> X + Ye- |
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Term
| An electron ______ potential energy when it shifts from a less electronegative atom toward a ____ electronegative one |
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Definition
| an electron loses potential energy when it shifts from a less electronegative atom toward a more electronegative one |
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Term
| NAD+ functions as an ____ during respiration |
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Definition
| NAD+ functions as an oxidizing agent during cellular respiration because it is an electron acceptor |
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Term
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Definition
a number of molecules, mostly proteins, that shuttle electrons from the "top" higher-end of the energy chain to the "bottom" lower-energy end. each "downhill" carrier is more electronegative than the last, and thus oxidizes its "uphill" neighbor. This creates an energy yielding tumble.
glucose --> NADH --> ETC --> oxygen |
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Term
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Definition
| NAD+ strips 2H from an organic fuel source and effectively neutralizes itself into NADH while releasing a H+ into the surrounding solution |
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Term
| what are the stages of cellular respiration? |
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Definition
1. glycolysis
2. pyruvate oxidation/citric acid cycle
3. oxidative phosphorylation: electron transport and chemisosmosis |
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Term
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Definition
| occurs in the cytosol, begins the degradation process by breaking glucose into two molecules of a pyruvate compound. no carbon is release as CO2, and it occurs whether or not O is present. consists of an energy investment and payoff phase |
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Term
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Definition
| completion of the breakdown of glucose to carbon dioxide, usually in the mitochondiron |
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Term
| oxidative phosphorylation |
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Definition
| the use of energy released in gylcolysis and citric acid cycle to fuel the electron transport train and subsequently synthesize ATP |
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Term
| substrate-level phosphorylation |
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Definition
| mode of ATP synthesis that occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP rather than adding an inorganic phosphate to ADP as in oxidative phosphorylation |
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Term
| how much ATP is made from each molecule of glucose degraded to carbon dioxide and water by respiration? |
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Definition
| the cell makes up to roughly 32 molecules of ATP, each with 7.3kcal/mol of free energy per molecule of glucose |
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Term
| what is the net energy yield from glycolysis, per glucose molecule? |
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Definition
| the net yield per glucose molecule from glycolysis is 2 ATP and 2NADH |
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Term
| how much carbon is released as CO2 during glycolysis? |
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Definition
| no carbon is released as CO2 during glycolysis |
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Term
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Definition
| Glycolysis does not need O2 to occur |
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Term
| what happens if O2 is present? |
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Definition
| if O2 is present, the chemical energy storyed in pyruvate and NADH can be extracted by pyruvate oxidation, the citric acid cycle, and phosphorylation |
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Term
| how much ATP is used during the energy investment phase of glycolysis? |
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Definition
| 2 ATP are used during the energy investment phase of glycolysis |
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Term
| what step links glycolysis and the citric acid cycle? |
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Definition
| the conversion of pyruvate to the compound acetyl coenzyme A is the step that links glycolysis to the citric acid cycle |
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Term
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Definition
| acetyl coenzyme A is the compound that pyrvate is converted to |
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Term
| the citric acid cycle (aka Kreb's Cycle) |
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Definition
| functions as a metabolic furnace that oxidizes organic fuel derived from pyruvate |
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Term
| where does most of the ATP produced by respiration come from? |
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Definition
| most of the ATP produced during respiration comes as a result of oxidative phosphorylation |
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Term
| what does the citric acid cycle function as? |
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Definition
| the citric acid cycle functions as a metabolic furnace that oxidizes organic fuel derived from pyruvate |
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Term
| where does the electron transport chain occur? |
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Definition
| the ETC is a collection of molecules embedded in the inner membrane of the mitochondrion in eukaryotic cells and reside in the plasma membrane of prokaryotes |
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Term
| what is the function of the ETC? |
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Definition
| the function of the ETC is not to make ATP directly, but to ease the fall of electrons from food to oxygen, breaking a large free-energy drop into a series of smaller steps that release energy in manageable amounts |
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Term
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Definition
| the enzyme that actually makes ATP, it is located on the inner membrane of the mitochondrion or the plasma membrane. works like an ion pump running in reverse, uses the energy of the H+ inon gradient to power ATP synthesis. the power comes from a difference in the concentration of H+ ion on opposite sides of the membrane. Is a multisubunit complex with four main parts. protons separately move to the binding sites of these proteins, causing the 'rotor' to spin in a way that catalyzes ATP productions. the flow of protons is thus like a stream turning a waterwheel |
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Term
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Definition
| the use of of energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as ATP synthesis |
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Term
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Definition
| the H+ gradient, emphasizes the capacity of the gradient to perform work. the force drives H+ back across the membrane through the H+ channels provided by ATP synthases |
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Term
| chesmiosmosis is a _____ _____ mechanism that uses energy stored in the for m of an __ ____ across a membrane to drive cellular work |
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Definition
| chemiosmosis is an energy-coupling mechanism that uses energy stored in the form of an H+ gradient across a membrane to drive cellular work |
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Term
| oxidative phosphorylation consists of two processes |
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Definition
| oxidative phosphorylation consists of electron transport chain and chemiosmosis |
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Term
| during respiration, most energy flows in this sequence: |
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Definition
| glucose --> NADA --> electron transport chain --> proton-motive force --> ATP |
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Term
| why can't we state the exact number of ATP molecules generated by the breakdown of one molecule of glucose |
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Definition
1. phosphorylation and the redox reactions are not directly coupled to each other, so the ration of the number of NDH molecules to the number of ATP molecules is not a whole number
2. the ATP yield varies slightly depending on the type of shuttle used to transport the electrons from the cytosol into the mitochondrion
3. the use of the proton-motive fore generated by the redox reactions of respirations reduces the yield of ATP |
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Term
| what is the estimate of the efficiency of respiration? |
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Definition
| the percentage of chemical energy in glucose that gets transffered to ATP during respiration is about 34% |
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Term
| what happens to the rest of the energy stored in glucose? |
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Definition
| the rest of the energy stored in glucose is lost as heat |
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Term
| what is the distinction between anaerobic respiration and fermentation? |
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Definition
| an ETC is used in anaerobic respiration but not in fermentation. however, the ETC used in anaerobic resp. does not use oxygen as a final electron acceptor at the end of the chain |
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Term
| fermentation harvests chemical energy without using _____ or ___- |
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Definition
| fermentation harvests energy without using oxygen or an ETC-- essentially without cellular respiration |
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Term
| how does fermentation generate ATP |
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Definition
| fermentation is an extension of glycolysis that allows the continues generation of ATP by the substrate-level phosphorylation of glycolysis |
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Term
| what is essential in fermentation |
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Definition
| for fermentation to occur, there needs to be a constant supply of NAD+ to accept electrons during the oxidation step of glycolysis |
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Term
| fermentation processes consist of |
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Definition
| fermentation consists of glycolysis plus reactions that regenerate NAD+ by transferring electrons from NADH to pyruvate or derivatives of pyruvate |
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Term
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Definition
| in alcohol fermentation pyruvate is converted to ethanol |
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Term
| what are the two steps of alcohol fermentation? |
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Definition
the two steps of alcohol fermentation?
1. C02 is released from the pyruvate, which is then convered to the two carbon compound acetaldehyde
2. the acetaldehyde is reduced by NADH to ethanol. this step regenerates the supply of NAD+ needed for the continuation of glycolysis |
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Term
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Definition
| during lactic acid fermentation pyruvate is reduced directly by NADH to form lactate as an end product, the no release of CO2 |
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Term
| what's the difference between alcohol and lactic acid fermentation? |
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Definition
| during alcoholic, CO2 is released while lactic acid does not release any CO2 |
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Term
| what do fermentation, anaerobic and aerobic respiration all have in common? |
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Definition
each of these pathways used glycolysis to oxidize glucose and other organic fuels to pyruvate, with a net production of 2 ATP by substrate-level phosphorylation.
NAD+ is the oxidizing agent that accepts electrons from food during glycolysis in all three pathways |
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Term
| what is a key difference between the three pathways |
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Definition
| a key difference between the three pathways is the contrasting mechanisms for oxidizing NADH back to NAD+ |
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Term
| how does fermentation convert NADH back to NAD+ |
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Definition
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Term
| what are the similarities between all three respiration pathways? |
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Definition
| all three pathways uses glycoloysis to oxidize glucose and other organic fuels to produce pyruvate, used substrate-level phosphorylation to produce a net of 2 ATP, and usage of NAD+ as an oxidizing agent that accepts electrons from food during glycolysis |
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Term
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Definition
| carry out only fermentation or anaerobic respiration, in fact these organisms cannot survive in the the presence of oxygen, some forms of which can actually be toxic if protective systems are not present in the cell |
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Term
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Definition
| cells in which pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes. under aerobic conditions, pyruvate can be converted to acetyl CoA, and oxidation continues in the citric acid cycle via aerobic respiration. Under anaerobic conditions, lactic acid fermentation occurs. basically these organisms can survive using either fermentation or cellular respiration |
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Term
| what does the wide spread use of glycolysis suggest about the orgin of organisms? |
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Definition
| the fact that glycolysis is today the ost widespread metabolic pathway on Earth suggests that it evolved very early in the history of life and the sytosolic location of glycolysis also implies great antiquity; the pathway does not require any of the membrane-bounded organelles of the eukaryotic cell |
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Term
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Definition
| a metabolic sequence that breaks the fatty acids down to two-carbon fragments, which enter the citric acid cycle as acetyl CoA. NADH and FADH2 are also generated |
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Term
| what is the most common mechanism for cellular control? |
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Definition
| the most common mechanism for control is feedback inhibition |
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Term
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Definition
| an important control switch, this is an allosteric enzyme that is inhibited by ATP and stimulated by AMP(derived from ADP) and catalyzes step 3 of glycolysis. this is the stem that commits the substrate irreversible to the glycolytic pathway, so by controlling the rate of this step the cell can speed up or slow down the entire catabolic process. phosphofructokinase is also sensitive to/ inhibited by citric acid, so as citrate accumulates, glycolysis slows down. |
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Term
| the break down of organic molecules is _____ |
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Definition
| the breakdown of organic molecules is exergonic |
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Term
| redox reactions in cellular respiration |
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Definition
| the transfer of electrons during chemical reactions releases energy stored in organic molecules and ultimately uses this energy to synthesize ATP |
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Term
| during cellular respiration ____ is oxidized, and ____ is reduced |
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Definition
| during cellular respiration, the fuel is oxidized, and O2 is reduced |
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Term
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Definition
| NAD+ functions as an oxidizing agent during cellular respiration to transfer electrons from organic compounds |
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Term
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Definition
| NADH in the ETC is the reduced form of NAD+ and represents the stored energy that is tapped to synthesize ATP |
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Term
| what are the three stages of cellular respiration? |
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Definition
1. glycolysis: breaks down glucose into two pyruvate molecules
2. Pyruvate oxidation and the citric acid cycle: completes the breakdown of glucoses
3. oxidative phosphorylation: electron transport and chemiosmosis: oxidative phosphorylation- account for most of the ATP synthesis |
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Term
| oxidative phosphorylation got its name because it utilizes what kind of reactions? |
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Definition
| oxidative phosphorylation got its name because it utilizes redox reactions |
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Term
| how much ATP synthesis can be accounted for with oxidative phosphorylation? |
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Definition
| 90% of the ATP generated by cellular respiration can be accounted for with oxidative phosphorylation |
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Term
| for each molecule of _____ degraded to CO2 and and water by respiration, the cell makes up to ______ molecules of ATP |
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Definition
| for each molecule of glucose reduced to CO2 and water during respiration, the cell makes up to 32 molecules of ATP |
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Term
| where does substrate-level phosphorylation occur? |
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Definition
| substrate-level phosphorylation occurs during glycolysis and the citric acid cycle |
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Term
| how does substrate-level phosphorylation occur? |
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Definition
| substrate-level phosphorylation occurs when a substrate bonded to an inorganic phosphate bonds to an enzyme that is also bonded to ADP. the inorganic phosphate is transferred to the ADP forming ATP and the substrate changes into the product. |
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Term
| where does glycolysis occur? |
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Definition
| glycolysis occurs in the cytoplasm |
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Term
| how does glycolysis harvest chemical energy? |
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Definition
| glycolysis harvests chemical energy by oxidizing glucose to pyruvate |
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Term
| what has to happen before the citric acid cycle can begin? |
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Definition
| before the citric acid cycle can begin, pyruvate must be converted into acetyl conenzyme A (CoA), which links glycolysis to the citric acid cycle |
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Term
| what does the citric acid cycle do? |
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Definition
| the citric acid cycle completes the oxidation of organic molecules (pyruvate) into to yield energy |
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Term
| what does the citric acid cycle yield? |
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Definition
| the citric acid cycle yields 1 ATP, 3 NADH, and 1 FADH2 per turn |
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Term
| during oxidative phosphorylation, _____ couples electron transport to ATP synthesis |
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Definition
| during oxidatvie phosphorylation, chemiosmosis couples electron transport to ATP synthesis |
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Term
| where does is the ETC located? |
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Definition
| the ETC is located in the inner membrane (cristae) of the mitochondrion |
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Term
| electrons drop in ____ ___ as the go down the chain and are finally passed to O2, forming ____ |
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Definition
| electrons drop in free energy as they go down the chain and are finally passed to O2, forming water |
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Term
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Definition
| proteins containing an iron atom in that are a part of the electron transport chain |
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Term
| the electron transport chain generates __ _____ directly |
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Definition
| the ETC generates no ATP directly |
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Term
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Definition
| the ETC breaks the large free energy drop from food to O2 into smaller steps that release energy into manageable amounts |
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Term
| electron transfer in the ETC causes what? |
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Definition
| electron transfer in the ETC causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space |
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Term
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Definition
| a proton that allows H+ exergonicaly to move back across the membrane and then uses this energy to drive phosphorylation of ATP |
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Term
| the energy stored in a H+ gradient across a membrane _____ the redox reactions of the ETC to ATP synthesis |
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Definition
| the energy stored in a H+ gradient across the membrane couples the redox reactions of the ETC to ATP synthesis |
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Term
| without ___, the ETC will cease to operate |
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Definition
| without O2 the ETC will cease to operate |
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Term
| in the case that O2 is not present, ____ couples with _____ or ____ ____ to produce ATP |
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Definition
| in the case that O2 is not present, glycolysis couples with fermentation or anaerobic respiration to produce ATP |
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Term
| _____ respiration uses an ETC with a final electron acceptor other than O2, for example sulfate |
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Definition
| anaerobic respiration uses an ETC with a final electron acceptor other than O2, for example sulfate |
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Term
| ____ uses substrate-level phosphorylation instead of ______ to generate ATP |
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Definition
| fermentation uses substrate-level phosphrylation instead of an ETC to generate ATP |
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Term
| fermentation consists of which to processes? |
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Definition
| fermentation consists of glycolysis and reactions that regenerate NAD+, which can then be reused by glycolysis |
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Term
| what's the difference between the two types of fermentation? |
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Definition
| in alcohol fermentation, ethanol is formed and CO2 is released while in lactic acid fermentation pyruvate is reduced to NADH forming lactate and no CO2 is released |
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Term
| give some examples of the different kinds of fermentation |
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Definition
alcohol: winemaking
lactic: muscles, cheese and yogurt, fungi |
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Term
| the final electron acceptor of fermentation is _____ while the final electron acceptor of cellular respiration is _____ |
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Definition
| the final electron acceptor of fermentation is an organic molecule while the final electron acceptor of cellular respiration is O2 |
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Term
| cellular respiration produces ___ ATP per glucose while fermentation produces ___ ATP per glucose |
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Definition
| cellular respiration produces 32 ATP per glucose while fermentation produces 2 ATP |
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Term
| evolutionary significance of glycolysis |
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Definition
| used to be very little O2 in the atmosphere, so it's likely ancient prokaryotes used only glycolysis to produce ATP, making it a very old process |
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Term
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Definition
| uses small molecules that come either directly from food or glycolysis or the citric acid cycle to build other substances |
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Term
| if ATP concentration begins to ___, respiration speeds up; when there is plenty of ATP, respiration______. |
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Definition
| if ATP concentration begins to drop, respiration speeds up; when there is plenty of ATP, respiration slows down |
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Term
| control of ____ is based mainly on regulating the activity of ____ at strategic points in the catabolic pathway |
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Definition
| control of catabolism is based on regulating the activity of enzymes at strategic points in the catabolic pathway |
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