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108 Cards in this Set
- Front
- Back
What is the name of the starting material of the citric acid cycle? |
Acetyl-coenzyme A |
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The citric acid cycle begins with the reaction between? |
acetyl-CoA and the four-carbon oxaloacetate to form six-carbon citric acid (Citrate) |
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During the eight reactions that take place, for every molecule of acetyl-CoA the cycle produces? |
2CO2 + 3 (NADH + H+) + 1 FADH2 + HS-CoA + 1GTP(ATP) |
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Stage 1 reactions and product |
Acetyl-CoA (2C) bonds with Oxaloacetate (4C) and produces Citrate (6C)
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What releases coenzyme A in Stage 1? |
A water molecule attacking the Acetyl releases the CoA |
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Stage 2 turns what into what product? |
Citrate (6C) ---> Isocitrate (6C)
Isomerization |
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Citrate Summary |
Stage 2 3 degree alcohol Isomerization Creates an isomer Isocitrate a 2 degree alcohol by a water molecule that is removed from the citric acid and then put back on in another location. |
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Isocitrate Summary |
Stage 3 2 degree alcohol Oxidation and Decarboxylation 2 events occur: NAD ---> NADH + H+ The enzyme isocitrate dehydrogenase catalyzes the oxidation of the –OH group at the 4' position of isocitrate to yield an intermediate which then has a carbon dioxide molecule removed from it to yield alpha-ketoglutarate. Release CO2 |
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Stage 3 product? |
Isocitrate (6C) ----> alpha - ketoglutarate (5C) Oxidation and Decarboxylation |
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Alpha - ketoglutarate Summary |
Stage 4 Oxidation and Decarboxylation 5 Carbon Ketone loses a carbon dioxide molecule and coenzyme A is added in its place. NAD ---> NADH + H+ release of CO2 |
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Succinyl-CoA Summary |
Stage 5 Hydrolysis 4 Carbon GTP synthesized Releases coenzyme CoA In this reaction, a free phosphate group first attacks the succinyl-CoA molecule releasing the CoA. After the phosphate is attached to the molecule, it is transferred to the GDP to form GTP. The resulting product is the molecule succinate |
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Stage 4 produces what? |
Alpha - ketoglutarate (5C) ---> Succinyl-CoA (4C) Oxidation and Decarboxylation |
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Stage 5 produces what? |
Succinyl-CoA (4C) ---> Succinate (4C) Hydrolysis |
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Hydrolysis |
the chemical breakdown of a compound due to reaction with water. |
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decarboxylation |
is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2) |
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Redox reaction |
Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction Oxidation is gain of oxygen Reduction is loss of oxygen Oxidising agents give oxygen to another substance Reducing agents remove oxygen from another substance |
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Stage 6 products |
Succinate (4C) ---> Fumarate (4C) Oxidation |
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Succinate Summary |
Stage 6 Oxidation 4 Carbon The enzyme succinate dehydrogenase catalyzes the removal of two hydrogens from succinate FAD ---> FADH2 (as it takes H from succinate) Makes a (C = C) bond Produces fumarate |
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Fumarate Summary |
Stage 7 Hydration 4 Carbon the addition of a water molecule to the fumarate in the form of an –OH group to yield the malate |
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Stage 7 produces |
Fumarate (4C) ---> Malate (4C) Hydration |
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Malate Summary |
Stage 8 Oxidation 4 Carbon regenerate oxaloacetate by oxidizing malate |
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Order of Citric Acid Cycle Reactions |
1 - aceytyl-CoA + oxaloacetate 2 - citrate 3 - isocitrate 4 - alpha-ketoglutarate 5 - succinyl-CoA 6 - succinate 7 - fumarate 8 - malate ---> oxaloacetate |
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Order of reactions that occur with each stage in the citric acid cycle |
1 - formation of citrate (coupling) 2 - isomerization 3 - oxidation and decarboxylation (redox) 4 - oxidation and decarboxylation (redox) 5 - hydrolysis 6 - oxidation (redox) 7 - hydration 8 - oxidation (redox) |
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4 Carbons? |
succinyl-CoA succinate fumarate malate oxaloacetate |
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6 Carbons? |
Citrate Isocitrate |
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The initial stage of the digestion of protein is catalyzed by an enzyme called ________. |
pepsin |
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The digestion of protein begins in the ________. |
stomach |
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An enzyme that can facilitate the breakdown of amylose into smaller units is ________. |
amylase |
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Digestion of carbohydrates begins in the ________. |
mouth |
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The components of ATP are ________. |
adenine, ribose, and three phosphate groups |
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The first stage of catabolism is ________. |
digestion of large molecules |
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Most of the energy in the typical animal cell is produced in the ________. |
mitochondria |
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How many main stages of catabolism are there? |
3 |
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What stage of metabolism involves the conversion of small molecules to CO2, H2O, and energy? |
Oxidation to CO2, H2O, and energy for ATP synthesis |
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What is meant by a catabolic reaction in metabolism? |
A reaction which breaks apart large molecules, releasing energy. |
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What is meant by an anabolic reaction in metabolism? |
An anabolic reaction uses energy in the cell to build large molecules needed by the cell. |
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Why is ATP considered an energy-rich compound? |
The hydrolysis of the phosphodiester bond in ATP releases energy that is sufficient for energy-requiring processes in the cell. |
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The digestion of fats begins where? |
in the small intestine |
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Identify coenzyme with riboflavin as a component |
FAD |
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Identify coenzyme with Adenine as a component |
NAD+ FAD |
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Identify coenzyme with aminoethanethiol as a component |
coenzyme A |
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If there are no reactions in the citric acid cycle that use oxygen, O2, why does the cycle operate only in aerobic conditions? |
The oxidized coenzymes NAD+ and FAD needed for the citric acid cycle are regenerated by the electron transport system. |
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What reduced coenzymes provide the electrons for electron transport? |
NADH FADH2 |
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What products of the citric acid cycle are needed for the electron transport chain? |
NADH FADH2 |
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What compounds are needed to start the citric acid cycle? |
The citric acid cycle begins by combining acetyl CoA and oxaloacetate. |
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Why is the citric acid cycle considered to be a metabolic cycle? |
In the citric acid cycle, oxaloacetate is regenerated, which is available to pick up acetyl CoA and start the cycle again. |
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Where in the cell are fatty acids normally oxidized? |
mitochondria |
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Where in the cell does the citric acid cycle take place? |
mitochondria |
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Which reaction(s) of the citric acid cycle involve(s) a direct phosphate transfer? |
reaction 5 This is the only time in the cycle that ATP is produced by a direct transfer of phosphate. Used to add a phosphate group to ADP to form ATP after GTP undergoes hydrolysis |
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Which reactions of the citric acid cycle involve oxidation and decarboxylation? |
reaction 3 & 4 |
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Which reactions of the citric acid cycle involve a hydration reaction? |
reaction 7 |
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Which reactions of the citric acid cycle reduce NAD+? |
reaction 3,4,8 |
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Which reactions of the citric acid cycle reduce FAD? |
reaction 6 |
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Oxidative phosphorylation |
synthesis of ATP from ADP + P, using energy generated by the oxidation reactions during electron transport |
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Choose an equation for the hydrolysis of ATP to ADP. |
ATP + H2O → ADP + Pi + 7.3 |
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Identify coenzyme with pantothenic acid as a component |
coenzyme A |
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Identify coenzyme with niacin as a component |
NAD+ |
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Identify coenzyme with ribitol as a component |
FAD |
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The energy released during electron transport is used to produce ________. |
ATP |
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In electron transport, NADH and FADH2 are used to provide ________. |
electrons and hydrogen ions |
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In electron transport, the synthesis of ATP from ADP + Pi is called ________. |
oxidative phosphorylation |
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The last reaction in the citric acid cycle converts malate to ________. |
oxaloacetate |
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In reaction 7 of the citric acid cycle, fumarate is converted to malate in a ________ reaction. |
hydration |
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In the dehydrogenation of succinate to fumarate in the citric acid cycle, the coenzyme used is ________. |
FAD |
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Reaction 5 of the citric acid cycle is the hydrolysis of succinyl-CoA. In this reaction, ________. |
the energy released is used to make GTP |
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The citric acid cycle reaction that removes the first CO2molecule is a(n) ________. |
oxidation and decarboxylation |
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In stage three of catabolism, the overall result is to release ________. |
carbon dioxide and energy |
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Which of the following compounds in the citric acid cycle undergoes oxidation and decarboxylation? |
isocitrate |
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What coenzyme(s) is(are) used in the citric acid cycle? |
NAD & FAD |
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FAD is a coenzyme which usually participates in ________. |
formation of carbon-carbon double bonds |
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NAD+ participates in reactions that produce ________ |
C=O bond |
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In biochemical systems, the term reduction often refers to ________. |
a gain of hydrogen or electrons by a compound |
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What is the purpose of digestion in stage 1? |
To break down the large molecules in food into smaller compounds that can be absorbed by the body. |
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Which of the metabolic pathways can occur in the absence of oxygen |
glycolysis |
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The middle stage of catabolism is the point at which |
acetyl CoA is produced |
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Protein synthesis takes place |
on the ribosomes |
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The main compound used to release energy for metabolism is |
adenosine triphosphate (ATP) |
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The final products of catabolic reactions are |
carbon dioxide, water, and ammonia |
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Coenzyme A is a molecule whose function is to |
acitvate acyl groups for reaction |
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An enzyme that can facilitate the breakdown of starch into smaller units is |
amylase |
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When combined with the electron transport chain, one turn of the citric acid cycle produces ____ ATP |
12 ATP |
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The citric acid cycle is used in the oxidation of |
glucose, fatty acids and proteins |
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IN the chemiosmotic model of oxidative phosphorylation, ATP is sythesized as |
H+ flows through ATP synthase |
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The components of the electron transport chain do NOT include |
acetyl CoA |
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In the electron transport chain, the oxidied product from the reaction of FMN + NADH + H+ is |
NAD+ |
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The electron carrier ______ provides 2 ATP via the electron transport chain |
FADH2 |
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In stage three of metabolism, the overall result is to release |
carbon dioxide and energy |
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In the dehydrogenation of succinate to fumarate in the citric acid cycle, the coenzyme used is |
FAD |
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In step 7 of the citric acid cycle, fumarate is converted to malate by a ______ reaction |
hydration |
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The compounds in electron transport that remove hydrogen ions and electrons from NADH are classified as |
electron carriers |
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One example of an electron carrier in the respiratory chain is |
coenzyme Q |
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In the chemiosmotic model, protons circulate through a protein complex called |
ATP synthase |
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In the activation of a fatty acid, energy from the hydrolysis of ATP is used to |
join the fatty acid to CoA |
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The digestion of fats begins when the fat globules are |
emulsified by bile salts |
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Fatty acids and glycerol are produced from the metabolism of |
lipids |
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The action of pancreatic lipase on tricylglycerols produces |
monoacylglycerols and free fatty acids |
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A chylomicron is a |
transport lipoprotein |
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The enzymes that break down triacylglycerols into fatty acids and glycerol are called |
lipases |
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The 2-carbon segments removed from a fatty acid during metabolism are used to form |
acetyl CoA |
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The 2-carbon units obtained by degradation of a fatty acid are further metabolized in |
the citric acid cycle |
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Each acetyl CoA produces _____ ATP in the citric acid cycle |
12 |
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This is the term that refers to all of the chemical reactions in living cells |
metabolism |
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The energy for most energy-requiring reactions in the cells of the body is obtained by the hydrolysis of ____ |
ATP |
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Most of the energy in our bodies is stored in the form of |
triacylglycerols |
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Hydrolysis of sucrose takes place primarily in the |
small intestine |
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The process that makes ATP using energy from the electron transport chain |
oxidative phosphorylation |
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The carrier of acetyl groups |
coenzyme A |
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CoA combines with this to form succinyl CoA in the krebs cycle. |
Alpha-ketogluterate |