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IPAP Biochemistry > Ch 22 Bio Exam 4 > Flashcards

Ch 22 Bio Exam 4 Flashcards

1
Q

Coenzyme A (CoA) is made up of several components:

A
  • pantothenic acid (vitamin B5)
  • phosphorylated ADP
  • aminoethanethiol
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2
Q

_______ is 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
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3
Q

____ is 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
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4
Q

The oxidized form of NAD+ undergoes _____ when a carbon atom in the nicotinamide ring reacts with 2H (two hydrogen ions and two electrons), leaving one H+.

A
  • reduction
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5
Q

_______ is used in anabolic reactions, such as lipid and nucleic acid synthesis.

A
  • NADP+, nicotinamide adenine dinucleotide phosphate
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6
Q

is similar to NAD+ except that a 2′ OH group is replaced by a phosphate group

A
  • NADP+, nicotinamide adenine dinucleotide phosphate
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7
Q

______ contains ADP and riboflavin (vitamin B2).

A
  • FAD, flavin adenine dinucleotide
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8
Q

_______ 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

A
  • FAD, flavin adenine dinucleotide
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9
Q

The ________ made from riboflavin (vitamin B2) and adenosine diphosphate is reduced to FADH2 by adding two hydrogen atoms.

A
  • coenzyme FAD (flavin adenine dinucleotide)
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10
Q

______ participates in reactions that produce a carbon-carbon double bond.

A
  • FAD, flavin adenine dinucleotide
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11
Q

FAD, flavin adenine dinucleotide is reduced to FADH2 with the aide of enzyme ______.

A
  • succinate dehydrogenase
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12
Q

Important functions of ______ include
preparation of small acyl groups such as acetyl for reactions with enzymes and production of the energy-rich thioester acetyl CoA.

A
  • coenzyme A
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13
Q

Glycolysis Reaction 1

A
  • Phosphorylation (ATP - ADP)
  • a phosphate group is transferred from ATP to glucose.
  • glucose-6-phosphate and ADP are produced.
  • the enzyme hexokinase catalyzes the reaction.
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14
Q

Glycolysis Reaction 2

A
  • Isomerization ( G6P and F6P are isomers)
  • glucose-6-phosphate, the aldose from reaction 1, is converted to fructose-6-phosphate.
  • the isomerization is catalyzed by the enzyme phosphoglucose isomerase
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15
Q

Glycolysis Reaction 3

A
  • phosphorylation
  • 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.
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16
Q

Glycolysis Reaction 4

A
  • cleavage,
  • fructose-1,6-bisphosphate is split into two three-carbon phosphate isomers.
  • the enzyme aldolase produces dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.
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17
Q

Glycolysis Reaction 5

A
  • isomerization,
  • 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.
18
Q

Glycolysis Reaction 6

A
  • oxidation and phosphorylation,
  • 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.
19
Q

Where are NADH molecules produced during Glycolysis?

A
  • # 2 NADH in reaction 6 of glycolysis
20
Q

Where are ATP molecules produced during Glycolysis?

A
  • # 2 in reaction 7 of glycolysis
  • # 2 in reaction 10 of glycolysis

Creating a net gain of 2 ATP overall

21
Q

Glycolysis Reaction 7

A
  • phosphate transfer
  • 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.
22
Q

Glycolysis Reaction 8

A
  • isomerization
  • 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.
23
Q

Glycolysis Reaction 9

A
  • dehydration
  • each phosphoglycerate molecule undergoes dehydration by the enzyme enolase.
  • two high-energy phosphoenolpyruvate molecules are produced.
24
Q

Glycolysis Reaction 10

A
  • phosphate transfer
  • 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.
25
Q

In muscles and kidneys, the intermediate monosaccharide fructose is phosphorylated to fructose-6-phosphate, which enters glycolysis in _____.

A
  • reaction 3
26
Q

Intermediate monosaccharide Galactose reacts with ATP to yield glucose-1-phosphate, which is converted to _______, which then enters glycolysis at ______.

A
  • glucose-6-phosphate

- reaction 2

27
Q

Glycolysis is regulated by three enzymes.

In reaction 1, _____ is inhibited by high levels of glucose-6-phosphate, which prevents the phosphorylation of glucose.

In reaction 3,______, an allosteric enzyme, is inhibited by high levels of ATP and activated by high levels of ADP and AMP.

In reaction 10, ______, another allosteric enzyme, is inhibited by high levels of ATP or acetyl CoA.

A
  • hexokinase
  • phosphofructokinase
  • pyruvate kinase
28
Q

______, is an important coenzyme required in the anabolic pathways, including the biosynthesis of nucleic acids, cholesterol, and fatty acids in the liver and fat cells.

A
  • NADPH, the reduced form of NADP+
29
Q

The ______ is an alternative pathway for the oxidation of glucose and produces the coenzyme NADPH and five-carbon pentoses.

A
  • pentose phosphate pathway
30
Q

The pentose phosphate pathway begins with glucose-6-phosphate from reaction 1 in glycolysis, which is converted to ____ and requires two NADP+.

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.

In a series of reactions, three ribose-5-phosphate molecules are converted to two hexose molecules and one triose molecule.

A
  • ribulose-5-phosphate
  • phosphopentose isomerase
  • 2 Fructose-6-phosphate + glyceraldhyde-3-phosphate
31
Q

Under aerobic conditions (oxygen present), where is pyruvate oxidized?

What coenzyme oxidizes it?

What other enzyme is involved in the final form of the reaction?

A
  • moves from the cytosol into the mitochondria to be oxidized further.
  • is oxidized when a carbon atom is removed as CO2 as the coenzyme NAD+ is reduced to NADH.
  • Pyruvate dehydrogenase, resulting two-carbon acetyl group is attached to CoA, producing acetyl CoA, an important intermediate in many metabolic pathways.
32
Q

How is pyruvate reduced to lactate under anaerobic conditions?

A
  • pyruvate is reduced to lactate and NAD+ by lactate dehydrogenase.
33
Q
  • occurs in anaerobic microorganisms, such as yeast.

- decarboxylates pyruvate to acetaldehyde, which is then reduced to ethanol, regenerating NAD+.

A
  • Fermentation
34
Q

During glycogenesis what enzyme converts glucose 6 p to glucose 1 p in reaction one?

A
  • the enzyme phosphoglucomutase catalyzing the shift of a phosphate group between carbon atoms.
35
Q

During reaction 2 of glycogenesis, g1p is converted to ____ by what enzyme?

A
  • UDP - glucose

- pyrophosphorylase and the addition of UMP.

36
Q

During reaction 3 of glycogenesis, what happens to UDP - glucose?

A
  • 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.

37
Q
  • glucose molecules are removed from the glycogen chain.

- glucose molecules are phosphorylated by glycogen phosphorylase to yield glucose-1-phosphate.

A
  • glycogenolysis, reaction 1
38
Q
  • glycogen phosphorylase 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.
A
  • glycogenolysis, reaction 2
39
Q
  • isomerization, the glucose-1-phosphate molecules are converted to glucose-6-phosphate molecules that enter the glycolysis pathway at reaction 2.
A
  • glycogenolysis, reaction 3
40
Q
  • dephosphorylation, cells in the liver and kidneys have a glucose-6-phosphatase that hydrolyzes the glucose-6-phosphate to yield free glucose.
A
  • glycogenolysis, reaction 4
41
Q

To protect the brain, hormones with opposing actions control blood glucose levels such as

A
  • glucagon,
  • insulin, and
  • epinephrine.

IPAP Biochemistry (5 decks)

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