Exam 4 - Chp. 22 - Metabolism Flashcards
(131 cards)
1
Q
that break down large, complex molecules to provide energy and smaller molecules.
A
catabolic reactions
2
Q
that use ATP energy to build larger molecules.
A
anabolic reactions
3
Q
Digestion and hydrolysis break down large molecules to smaller ones that enter the bloodstream
A
Stage 1 Catabolic reactions
4
Q
Within the cells, degradation breaks down molecules to two- and three-carbon compounds
A
Stage 2 Catabolic reactions
5
Q
Oxidation of small molecules in the citric acid cycle and electron transport provides ATP energy.
A
Stage 3 Catabolic reaction
6
Q
In the three stages of catabolism, large molecules from foods are digested and degraded to provide smaller molecules that can be ___ to produce energy.
A
oxidized
7
Q
Cells in plants and animals are known as ___ cells, which have a nucleus that contains DNA.
A
eukaryotic
8
Q
a cell membrane separates the materials inside the cell from the aqueous environment surrounding the cell.
the cell nucleus contains the genes that control DNA replication and protein synthesis.
the cytosol, or fluid part of the cell, contains electrolytes and enzymes that catalyze chemical reactions in the cell.
A
Animal cells
9
Q
The ATP molecule, composed of ___, hydrolyzes to form ADP and AMP along with a release of energy.
A
the base adenine, a ribose sugar, and three phosphate groups
10
Q
The hydrolysis of ATP to ADP releases __ kcal (31 kJ) per mole
A
7.3
11
Q
The hydrolysis of ADP to AMP releases __ kcal (31 kJ) per mole
A
7.3
12
Q
When ATP __, the energy released can be used to drive an energy-requiring reaction
A
hydrolyzes
13
Q
used in anabolic reactions
the energy-storage molecule
combined with energy-requiring reactions
A
ATP
14
Q
hydrolysis products
A
ADP + Pi
15
Q
Coenzyme A (CoA) is made up of several components: pantothenic acid (vitamin B5), phosphorylated ADP, and ___
A
aminoethanethiol
16
Q
Metabolic reactions that extract energy from food involve both ___ reactions
A
oxidation and reduction
17
Q
involves the loss of hydrogen or electrons by a substance or an increase in the number of bonds to oxygen
A
Oxidation
18
Q
gain of hydrogen ions and electrons or a decrease in the number of bonds to oxygen
A
Reduction
19
Q
In both types of reactions, coenzymes are required to carry the ___ and electrons from or to the reacting substrate.
A
hydrogen ions
20
Q
A coenzyme that gains hydrogen ions and electrons is __, whereas a coenzyme that loses hydrogen ions and electrons to a substrate is __
A
reduced
oxidized
21
Q
an important coenzyme in which the vitamin niacin provides the nicotinamide group, which is bonded to ribose and the nucleotide adenosine diphosphate (ADP).
A
NAD+, nicotinamide adenine dinucleotide,
22
Q
required in dehydrogenation reactions that produce carbon–oxygen double bonds, such as the oxidation of alcohols to aldehydes and ketones
A
NAD+, nicotinamide adenine dinucleotide
23
Q
The ___ form of NAD+ undergoes reduction when a carbon atom in the nicotinamide ring reacts with 2H (two hydrogen ions and two electrons), leaving one H+.
A
oxidized
24
Q
used in anabolic reactions, such as lipid and nucleic acid synthesis
A
NADP+, nicotinamide adenine dinucleotide phosphate
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similar to NAD+ except that a 2′ OH group is replaced by a phosphate group
NADP+, nicotinamide adenine dinucleotide phosphate
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reduced to form NADPH
NADP+, nicotinamide adenine dinucleotide phosphate
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contains ADP and riboflavin (vitamin B2).
FAD, flavin adenine dinucleotide,
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undergoes reduction when the two nitrogen atoms in the flavin part of the FAD coenzyme react with two hydrogen atoms (2H+ + 2 e−), reducing it to FADH2.
FAD, flavin adenine dinucleotide
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The coenzyme FAD (flavin adenine dinucleotide) made from riboflavin (vitamin B2) and adenosine diphosphate is reduced to FADH2 by adding ____
two hydrogen atoms.
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participates in reactions that produce a carbon-carbon double bond.
FAD, flavin adenine dinucleotide,
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reduced to FADH2 with the aide of enzyme succinate dehydrogenase
FAD, flavin adenine dinucleotide,
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____ is derived from a phosphorylated ADP and pantothenic acid bonded by an amide bond to aminoethanethiol, which contains the —SH reactive part of the molecule.
Coenzyme A
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preparation of small acyl groups such as acetyl for reactions with enzymes.
Important functions of coenzyme A include
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production of the energy-rich thioester acetyl CoA.
Important functions of coenzyme A include
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coenzyme used in oxidation of carbon-oxygen bonds
NAD+
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reduced form of flavin adenine dinucleotide
FADH2
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used to transfer acetyl groups
coenzyme A
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contains riboflavin
FAD, FADH2
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the coenzyme after C = O bond formation
NADH + H+
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Carbohydrate digestion begins in the mouth, where ___ breaks down polysaccharides into smaller polysaccharides (dextrins), maltose, and some glucose
salivary amylase
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In the stomach, the partially digested starches enter the acidic environment, where the ___ stops further carbohydrate digestion
low pH
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In the small intestine where the pH is about 8,
| enzymes produced in the pancreas ____ the remaining dextrins to maltose and glucose
hydrolyze
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In the small intestine where the pH is about 8, enzymes produced in the mucosal cells that line the small intestine ___ maltose, lactose, and sucrose
hydrolyze
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In the small intestine where the pH is about 8, the resulting ___ are absorbed through the intestinal wall into the bloodstream
monosaccharides
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In the liver, hexoses fructose and galactose are converted to ___, the primary energy source for muscle contractions, red blood cells, and the brain.
glucose
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Glucose in the bloodstream enters our cells, where it undergoes ___ in a pathway called glycolysis.
degradation
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Glucose obtained from the digestion of polysaccharides is degraded in glycolysis to ___.
pyruvate
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takes place in the cytosol of the cell.
is a metabolic pathway that uses glucose, a digestion product.
degrades six-carbon glucose molecules to three-carbon pyruvate molecules
Glycolysis
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energy is required to add phosphate groups to glucose.
glucose is converted to two three-carbon molecules
Reactions 1–5 of glycolysis
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energy is obtained from the hydrolysis of the energy-rich phosphate compounds.
four ATP molecules are synthesized
reactions 6–10 of glycolysis
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a phosphate group is transferred from ATP to glucose.
glucose-6-phosphate and ADP are produced.
the enzyme hexokinase catalyzes the reaction
reaction 1, phosphorylation
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glucose-6-phosphate, the aldose from reaction 1, is converted to fructose-6-phosphate.
the isomerization is catalyzed by the enzyme phosphoglucose isomerase
reaction 2, isomerization,
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hydrolysis of another ATP provides a second phosphate group.
the phosphate group is transferred to fructose-6-phosphate, producing fructose-1,6-bisphosphate.
a second kinase enzyme called phosphofructokinase catalyzes the reaction.
reaction 3, phosphorylation
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fructose-1,6-bisphosphate is split into two three-carbon phosphate isomers.
the enzyme aldolase produces dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.
reaction 4, cleavage
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dihydroxyacetone phosphate undergoes isomerization catalyzed by triose phosphate isomerase.
a second molecule of glyceraldehyde-3-phosphate is produced, which can be oxidized.
all six carbon atoms from glucose are contained in two identical triose phosphates
reaction 5, isomerization
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In reaction 5, isomerization,
_____ undergoes isomerization catalyzed by triose phosphate isomerase.
a second molecule of ____ is produced, which can be oxidized.
all six carbon atoms from glucose are contained in two identical ____.
dihydroxyacetone phosphate
glyceraldehyde-3-phosphate
triose phosphates
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the aldehyde group of each glyceraldehyde-3-phosphate is oxidized to a carboxyl group.
NAD+ is reduced to NADH and H+.
a phosphate group is transferred to each of the new carboxyl groups, forming two molecules of 1,3-bisphosphoglycerate.
In reaction 6, oxidation and phosphorylation
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In reaction 6, oxidation and phosphorylation, the aldehyde group of each ____ is oxidized to a carboxyl group.
NAD+ is reduced to NADH and H+.
a phosphate group is transferred to each of the new carboxyl groups, forming two molecules of _____
glyceraldehyde-3-phosphate
1,3-bisphosphoglycerate
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a phosphate group from each 1,3-bisphosphoglycerate is transferred to two ADP molecules by phosphoglycerate kinase.
two molecules of the high-energy compound ATP are produced.
reaction 7, phosphate transfer
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reaction 7, phosphate transfer, a phosphate group from each ____ is transferred to two ADP molecules by phosphoglycerate kinase.
two molecules of the high-energy compound ATP are produced.
1,3-bisphosphoglycerate
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two 3-phosphoglycerate molecules undergo isomerization by phosphoglycerate mutase.
the phosphate group is moved from carbon 3 to carbon 2, yielding two molecules of 2-phosphoglycerate.
reaction 8, isomerization
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In reaction 8, isomerization, two 3-phosphoglycerate molecules undergo isomerization by ___.
the phosphate group is moved from carbon 3 to carbon 2, yielding two molecules of 2-phosphoglycerate.
phosphoglycerate mutase
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each phosphoglycerate molecule undergoes dehydration by the enzyme enolase.
two high-energy phosphoenolpyruvate molecules are produced
reaction 9, dehydration
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In reaction 9, dehydration, each ___ molecule undergoes dehydration by the enzyme enolase.
two high-energy phosphoenolpyruvate molecules are produced.
phosphoglycerate
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phosphate groups from two phosphoenolpyruvate molecules are transferred by pyruvate kinase to two ADPs, to yield two pyruvates, and two ATPs.
a fourth kinase enzyme transfers a phosphate with ATP production.
In reaction 10, phosphate transfer,
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In reaction 10, phosphate transfer, phosphate groups from two ___molecules are transferred by pyruvate kinase to two ADPs, to yield two pyruvates, and two ATPs.
a fourth kinase enzyme transfers a phosphate with ATP production.
phosphoenolpyruvate
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two ATP molecules add phosphate to glucose and fructose-6-phosphate.
four ATP molecules are formed in energy generation by direct transfers of phosphate groups to four ADP.
there is a net gain of two ATPs and two NADHs.
glycolysis
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Other monosaccharides, such as ___, can enter glycolysis after they are converted to intermediates.
fructose and galactose
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In muscles and kidneys, fructose is phosphorylated to ___, which enters glycolysis in reaction 3
fructose-6-phosphate
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Galactose reacts with ATP to yield ___, which is converted to glucose-6-phosphate, which then enters glycolysis at reaction 2.
galactose-1-phosphate
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In glycolysis reaction 1, __ is inhibited by high levels of glucose-6-phosphate, which prevents the phosphorylation of glucose.
hexokinase
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In glycolysis reaction 3, ___, an allosteric enzyme, is inhibited by high levels of ATP and activated by high levels of ADP and AMP
phosphofructokinase
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In glycolysis reaction 10, ___, another allosteric enzyme, is inhibited by high levels of ATP or acetyl CoA
pyruvate kinase
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In glycolysis reaction 7, phosphate groups from two
| ____ molecules are transferred to ADP to form two ATPs
1,3-bisphosphoglycerate
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In glycolysis reaction 10, phosphate groups from two ____ molecules are used to form two more ATPs.
phosphoenolpyruvate
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an alternative pathway for the oxidation of glucose.
| produces the coenzyme NADPH and five-carbon pentoses
pentose phosphate pathway
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NADPH, the reduced form of NADP+, is an important ___ required in the anabolic pathways, including the biosynthesis of nucleic acids, cholesterol, and fatty acids in the liver and fat cells.
coenzyme
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pentose phosphate pathway begins with glucose-6-phosphate from reaction 1 in glycolysis, which is converted to ___ and requires two NADP+.
ribulose-5-phosphate
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Ribulose-5-phosphate is isomerized by the catalyst ___ to ribose-5-phosphate, an important component of nucleotides such as ATP, GTP, UTP, NAD+, FAD, and RNA
phosphopentose isomerase
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In a series of reactions, three ___ molecules are converted to two hexose molecules and one triose molecule
ribose-5-phosphate
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The pentose phosphate pathway converts glucose-6-P to ___, which is needed for the synthesis of DNA and RNA
ribose-5-P
Ribose-5-P can also return to glycolysis as needed.
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Lactate is transported to the liver, where it is converted back into
pyruvate.
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Under aerobic conditions, oxygen is available to convert ___ to acetyl coenzyme A (acetyl CoA) and CO2.
pyruvate
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When oxygen levels are low, pyruvate is reduced to
lactate
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Under aerobic conditions (oxygen present), pyruvate
| moves from the __into the mitochondria to be oxidized further
cytosol
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Under aerobic conditions (oxygen present), ___ is oxidized when a carbon atom is removed as CO2 as the coenzyme NAD+ is reduced
pyruvate
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The resulting two-carbon acetyl group is attached to CoA, producing ____, an important intermediate in many metabolic pathways.
acetyl CoA,
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Under anaerobic conditions (without oxygen),
pyruvate is reduced to lactate and NAD+ by lactate dehydrogenase.
NAD+ is used to oxidize ___ in the glycolysis pathway, producing a small amount of ATP.
glyceraldehyde-3-phosphate
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The accumulation of ___ causes the muscles to tire and become sore. Lactate is subsequently transported to the liver and converted back to pyruvate.
lactate
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Under anaerobic conditions, the only ATP production in glycolysis occurs during the steps that ___ ADP directly giving a net gain of only two ATP.
phosphorylate
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occurs in anaerobic microorganisms, such as yeast.
| decarboxylates pyruvate to acetaldehyde, which is then reduced to ethanol, regenerating NAD+.
Fermentation
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During fermentation, enzymes in the yeast convert sugars to glucose and then to ___ and CO2 gas
ethanol
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produced during anaerobic conditions
lactate
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reaction series that converts glucose to pyruvate
glycolysis
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metabolic reactions that break down large molecules to smaller molecules + energy reactions
catabolic
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substances that remove or add H atoms in oxidation and reduction reactions
coenzymes
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Glycogen storage diseases (GSDs) occur when a defective ___ is involved in a pathway for glycogen storage or degradation.
enzyme
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is a polymer of glucose with α(1 -> 4)-glycosidic bonds and multiple branches attached by α(1 -> 6)-glycosidic bonds.
Glycogen
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is formed when high levels of glucose-6-phosphate are formed in the first reaction of glycolysis.
Glycogen
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not formed when energy stores (glycogen) are full, which means that additional glucose is converted to triacylglycerols and stored as body fat.
Glycogen
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metabolic process of converting glucose molecules into glycogen.
Glycogenesis
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produces glucose-6-phosphate in reaction 1 of glycolysis.
Glycogenesis
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the conversion of glucose-6-phosphate to the isomer glucose-1-phosphate.
the enzyme phosphoglucomutase catalyzing the shift of a phosphate group between carbon atoms.
Glycogenesis: Reaction 1
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glucose-1-phosphate is activated before addition to the glycogen chain.
energy is released when pyrophosphorylase catalyzes the reaction.
the high-energy compound UTP transfers UMP to glucose-1-phosphate to give UDP-glucose and pyrophosphate, PPi.
Glycogenesis: Reaction 2
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Glycogenesis: Reaction 2, glucose-1-phosphate is activated before addition to the glycogen chain.
energy is released when pyrophosphorylase catalyzes the reaction.
the high-energy compound UTP transfers UMP to glucose-1-phosphate to give ___
UDP-glucose and pyrophosphate, PPi
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glycogen synthase catalyzes breaking of the phosphate bond to glucose in UDP-glucose.
glucose is released, forming an α(1 -> 4) glycosidic bond with the end of a glycogen chain.
Glycogenesis: Reaction 3
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In glycogenolyis reaction 1, phosphorolysis,
glucose molecules are removed from the glycogen chain.
glucose molecules are phosphorylated by glycogen phosphorylase to yield __
glucose-1-phosphate.
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In reaction 2, hydrolysis (α-1,6),
____ cleaves α(1 ,4)-links until only one glucose remains bonded to the main chain.
a debranching enzyme breaks α(1 , 6)-glycosidic bonds so branches of glucose molecules can be hydrolyzed by reaction 1.
glycogen phosphorylase
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Glycogenolysis: Reaction 3, isomerization, the glucose-1-phosphate molecules are converted to ___ molecules that enter the glycolysis pathway at reaction 2
glucose-6-phosphate
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In glycogenolysis reaction 4, dephosphorylation, cells in the liver and kidneys have a glucose-6-phosphatase that hydrolyzes the glucose-6-phosphate to yield
free glucose.
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activated by low levels of blood glucose
converts glucose-1-phosphate to glucose-6-phosphate
glycogenolysis
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activated by high levels of glucose-6-phosphate
glucose + UTP UDP-glucose + Ppi
glycogenesis
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Glucose is synthesized in the tissues of the ___.
| Tissues that use glucose as their main energy source are the brain, skeletal muscles, and red blood cells
liver and kidneys
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If our glycogen stores are depleted,
liver cells synthesize glucose by ___.
Glucose is synthesized in the cytosol of the liver cells, and some is synthesized in the kidneys
gluconeogenesis
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can supply us with about one day’s requirement of glucose.
is made from glucose, most of which is synthesized in the cytosol of liver cells
Glycogen
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To begin gluconeogenesis, carbon atoms from ____ food sources are converted to pyruvate.
noncarbohydrate
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To start the synthesis of glucose from pyruvate,
two catalyzed reactions are needed to replace reaction 10 in glycolysis.
_____ uses the energy of ATP hydrolysis to catalyze the addition of CO2 to pyruvate and produce oxaloacetate.
______ converts oxaloacetate to phosphoenolpyruvate.
phosphoenolpyruvate molecules now use enzymes to form fructose-1,6-bisphosphate.
pyruvate carboxylase
phosphoenolpyruvate carboxykinase
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The second irreversible reaction in glycolysis is bypassed when ___ cleaves a phosphate group from fructose-1,6-bisphosphate.
fructose-1,6-bisphosphatase
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The product fructose-6-phosphate undergoes the reversible reaction 2 of glycolysis to yield
glucose-6-phosphate
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In the final irreversible reaction, the phosphate group of glucose-6-phosphate is hydrolyzed by a different enzyme, glucose-6-phosphatase, to form ___.
glucose
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Gluconeogenese: The pathway consists of seven reversible reactions of glycolysis and four new reactions that replace the three irreversible reactions
Overall, glucose synthesis requires four ATPs, two GTPs, and two NADHs.
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is the flow of lactate and glucose between the muscles and the liver.
occurs when anaerobic conditions occur in active muscle, and glycolysis produces lactate
Cori cycle
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operates when lactate moves through the blood stream to the liver, where it is oxidized back to pyruvate.
converts pyruvate to glucose, which is carried back to the muscles
Cori cycle
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not utilized when the diet is high in carbohydrates.
Gluconeogenesis
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very active when the diet is low in carbohydrates.
Gluconeogenesis
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When conditions in a cell favor glycolysis, there is no synthesis of
glucose
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When the cell requires the synthesis of glucose, ___is turned off.
glycolysis
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the synthesis of glucose from noncarbohydrates
gluconeogenesis
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the breakdown of glycogen into glucose
glycogenolysis
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the oxidation of glucose to two pyruvate
glycolysis
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the synthesis of glycogen from glucose
glycogenesis
