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DEN 7101F - Human Structure and Function > Exam 2 10/25 Howard > Flashcards

Exam 2 10/25 Howard Flashcards

1
Q

Definition of metabolism

A
  • sum of all physical/chemical processes by which living organized substance is produce and maintained
  • transformation by which energy is made available for the uses of the organism
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2
Q

Cells extract energy from:

A
  • food
  • energy stores
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3
Q

Catabolism: releases or requires energy?

A

Releases energy

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4
Q

Anabolism: releases or requires energy?

A

Requires energy

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5
Q

Catabolism

A

Degradation of larger molecules into smaller ones

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6
Q

Anabolism

A

Conversion of monomers into polymers of more complex molecules

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7
Q

Catabolism - overall reaction

A

Fuel (carbohydrates, fats) –> CO2 + H2O + useful energy

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8
Q

Catabolism involves metabolic reactions that _____ energy through the use of simple organic compounds. Most involve _____

A

Yield energy; oxidative degradation

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9
Q

Oxidation means

A

Loss of electrons

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10
Q

Degradation is also known as

A

Catabolism

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11
Q

Biosynthetic is also known as

A

Anabolism

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12
Q

Anabolism overall reaction

A

Useful energy + simple precursors –> complex molecules

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13
Q

Anabolism involves metabolic reactions that ____ and _____. Most involve ____ biosynthesis

A

use energy and create macromolecules; reductive

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14
Q

Reduction is

A

gain of electrons

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15
Q

True or false: regarding catabolism and anabolism, the pathways are distinct

A

True - not a reversal of the same pathway and located in different compartments

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16
Q

Synthetic reactions are found in the:

A

Cytosol

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17
Q

Oxidation reactions are found in the:

A

Mitochondria

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18
Q

General principles of metabolism (3)

A
  1. fuels are degraded, large molecules are constructed through step by step metabolic pathways
  2. Common energy currency (ATP) links energy-releasing pathways with energy requiring pathways
  3. Oxidation of carbon fuels powers formation of ATP
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19
Q

In metabolism, there is a highly integrated network of over 1000 chemical reactions, but there are 4 common motifs, which are:

A
  1. energy currency
  2. limited number of activated intermediates
  3. types of reactions is small
  4. regulated in common ways
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20
Q

___ molecules play a central role in metabolism

A

100

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21
Q

What types of chemical reactions are found in metabolism?

A
  1. Oxidation-reduction
  2. Ligation requiring ATP cleavage (forms covalent bonds)
  3. Isomerization
  4. Group transfer
  5. Hydrolytic
  6. Additional or removal of functional groups
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22
Q

Methods of regulation of metabolic reactions

A
  1. amount of enzymes
  2. enzymes catalytic activity
  3. accessibility of substrate
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23
Q

The amount of enzymes is controlled by

A

Rate of synthesis, rate of degradation

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24
Q

Enzyme catalytic activity is controlled by

A
  • reversible allosteric control
  • feedback inhibition
  • reversible covalent modification
  • hormones coordinate activities
  • ratio of ATP to ADP
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25
Q

Accessibility of substrate is controlled by:

A
  • compartmentation which separates opposing reactions
  • control of flux of substrates
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26
Q

Reaction can only occur spontaneously if:

A

ΔG is negative

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27
Q

Metabolic pathways can couple _____

A

Individual reactions

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28
Q

Two criteria for coupling individual reactions

A
  • reactions must be specific
  • sum of reactions must be thermodynamically favorable (-ΔG)
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29
Q

What do coupled reactions share?

A

Same intermediate (product of one reaction is the reactant for the next)

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30
Q

A thermodynamically unfavorable reaction is driven by:

A

a favorable reaction
(reactions are coupled by shared intermediate)

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31
Q

Examples of special molecules that act as carriers between metabolic reactions

A
  • ATP
  • NADH/NADPH
  • FADH2
  • Coenzyme A
  • Biotin
  • Tetrahydrofolate
  • S-Adenosylmethionine
  • Uridine Diphosphate glucose
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32
Q

Phosphoryl group is carried by

A

ATP
Phosphoenolpyruvate (PEP, high energy)

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33
Q

Electrons are carried by

A
  • NADH
  • NADPH
  • FADH2
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34
Q

Acyl group is carried by

A

Coenzyme A

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35
Q

CO2 group is carried by

A

Biotin

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36
Q

One-carbon units are carried by

A

Tetrahydrofolate

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37
Q

Methyl groups are carried by

A

S-adenosylmethionine

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38
Q

Glucose group is carried by

A

Uridine Diphosphate Glucose

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39
Q

____ are unifying motifs of biochemistry

A

Carrier molecules (ATP most familiar)

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40
Q

What is the universal energy carrier?

A

ATP

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41
Q

What process produces free energy (ATP)?

A

Oxidative degradation

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42
Q

Energy stored in ATP is conserved via:

A

High energy chemical bonds

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43
Q

ATP is a ____ made of ____

A

Nucleotide; adenine, ribose, triphosphate

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44
Q

ATP contains ____ phosphoanhydride bonds

A

2

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45
Q

True or false: ATP stores energy transiently to do work

A

True - transient store of energy, made and degraded over and over again

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46
Q

Phosphoanhydride bond is a type of:

A

Covalent bond

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47
Q

High energy phosphoanhydride bond is formed via:

A
  • condensation of 2 molecules of phosphate (PO43-)
  • subsequent loss of water (condensation reaction)
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48
Q

When phosphoanhydride bonds are broken, ____ is released

A

Large amounts of energy

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49
Q

Principle immediate donor of free energy

A

ATP

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50
Q

True or false: ATP serves as storage of free energy

A

False - does not; ATP turnover is high and must be continuously regenerated from ADP

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51
Q

A highly favorable reaction has:

A

A large change in free energy

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52
Q

An energy-yielding reaction results in:

A

Synthesis of ATP

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53
Q

An energy-requiring reactions uses ____

A

ATP

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54
Q

Examples of energy-requiring reactions

A
  • performance of mechanical work (muscle contraction, cellular movements)
  • active transport of molecules and ions
  • synthesis of macromolecules from simple precursors
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55
Q

Fundamental mode of energy exchange

A

ATP-ADP cycle

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56
Q

____ can drive unfavorable reactions

A

ATP hydrolysis

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57
Q

ATP hydrolysis can change the equilibrium ratio of products to reactants by

A

10^5 (reaction by itself compared to coupled with ATP hydrolysis)

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58
Q

True or false: ATP is the only carrier of phosphoryl groups

A

False - there are many others (phosphoenolpyruvate, creatine phosphate, pyrophosphate, etc.)

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59
Q

Phosphoryl-transfer potential is an important form of:

A

Energy conversion

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60
Q

ATP is a phosphate ____

A

Donor

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61
Q

ADP is a phosphate ____

A

Acceptor

62
Q

ATP to ADP free energy number

A
  • 7.3
63
Q

Phosphoenolpyruvate free energy number

A
  • 14.8
64
Q

How does phosphoenolpyruvate help create ATP?

A

transfers phosphoryl group to ADP in breakdown of glucose

65
Q

Creatine phosphate is used in _____ and serves as:

A

muscle; reservoir of high energy phosphoryl groups that can be transferred to ADP

66
Q

Many activated carriers are derived from _____

A

water-soluble vitamins

67
Q

NADH/NADPH are derived from what vitamin?

A

Nicotinate (niacin) B3

68
Q

FADH2 is derived from what vitamin?

A

Riboflavin (vitamin B2)

69
Q

Coenzyme A is derived from what vitamin?

A

Pantothenate B5

70
Q

Tetrahydrofolate is derived from what vitamin?

A

Folate

71
Q

NADH and FADH2 are major electron carriers in the _____

A

oxidation of fuels

72
Q

NADH and FADH2 are used during

A
  • oxidation glucose and fatty acids
  • electrons transferred using these carrier molecules
73
Q

NAD+ stands for

A

Nicotinamide adenine dinucleotide

73
Q

Under aerobic conditions, the ultimate electron acceptor is:

A

O2

74
Q

NAD+ is a

A

pyridine dinucleotide

75
Q

FAD stands for

A

Flavin adenine dinucleotide

76
Q

FAD is a ___ compound

A

Flavin

77
Q

The reactive part of NAD+ is:

A

Nicotinamide ring

78
Q

In NAD+, the pyridine derivative is synthesized from:

A

niacin (B3)

79
Q

NAD+ accepts ____ and ____

A

1 hydrogen ion; 2 electrons

80
Q

Reduced form of NAD+/function?

A

NADH; passes electrons to oxygen

81
Q

Reaction with NAD+ is called:

A

Dehydrogenation reaction

82
Q

Where is the reactive site of FAD?

A

Flavin ring (on nitrogens where hydrogens can be accepted)

83
Q

FAD contains what kind of bond?

A

Phosphoanhydride bond (1)

84
Q

Structure of the oxidized form of FAD contains:

A
  • FMN unit (flavin mononucleotide)
  • AMP unit
85
Q

When FAD is reduced, it accepts:

A
  • 2 electrons
  • 2 hydrogen ions
86
Q

What is the difference between NAD+ and NADP+?

A
  • NADP+ has a phosphate group at 2’ position of the adenosine moiety (acts as a tag for enzyme recognition)
  • carries electrons the same way but dif function (NADP+ is an electron donor for reductive biosynthesis)
87
Q

With NADPH, ____ is needed in addition to ATP

A

reducing power

88
Q

Coenzyme A reactive group?

A

terminal sulfhydryl

89
Q

Coenzyme A transfers ____ groups in many _____ reactions

A

acyl groups; enzyme-catalyzed acylation reactions

90
Q

Acyl CoA and Acetyl CoA have an _____ which has potential for

A

activated acetyl group; high acetyl group transfer potentialIn

91
Q

In Coenzyme A, what is found on the 3’ end?

A

3’-Phospho-ADP

92
Q

Acyl CoA and Acetyl CoA have what kind of bond?

A

Thioester bond

93
Q

Stages in the extraction of energy from food (3)

A

Stage 1: digestion (fats, polysaccharides, proteins broken down)
Stage 2: Small molecules converted to Acetyl CoA (little ATP formed)
Stage 3: Consists of TCA cycle, Oxidative phosphorylation to form ATP; 4 pairs of e- transferred from acetyl unit

94
Q

Vast majority of ATP is formed via

A

Oxidative phosphorylation

95
Q

Stages in glucose oxidation (4)

A
  1. Glycolysis - 1 glucose to 2 pyruvate molecules
  2. TCA cycle - pyruvate oxidation to CO2
  3. Electron transport chain to generate proton-motive force
  4. ATP synthesis
96
Q

Where does glycolysis occur?

A

In the cytosol

97
Q

Net products of glycolysis

A
  • 2 ATP
  • 2 NADH
  • 2 Pyruvate
98
Q

All glycolysis intermediates are:

A

Water soluble, phosphorylated molecules

99
Q

Stage 1 of glycolysis involves _____, and Stage 2 of glycolysis involves _____

A

trapping glucose in cell; harvesting a small amount of ATP to produce pyruvate

100
Q

____ traps glucose

A

Hexokinase

101
Q

1st irreversible step of glycolysis

A

Glucose is phosphorylated by hexokinase

102
Q

Hexokinase is inhibited by:

A

G6P

103
Q

Hexokinase Km

A

0.2 mmol/L

104
Q

Hexokinase has a ____ affinity for its substrate (glucose)

A

High

105
Q

Glucokinase

A

Special liver form of hexokinase enzyme

106
Q

Glucokinase Km

A

10 mmol/L

107
Q

Is glucokinase feedback regulated?

A

No

108
Q

High glucose levels drive the formation of:

A

Glycogen (storage of glucose)

109
Q

Glucokinase has a ____ affinity for its substrate (glucose)

A

Low (high Km)

110
Q

Km has a direct/reciprocal relationship with substrate affinity?

A

Reciprocal - High Km = low affinity for substrate

111
Q

Liver maintains blood glucose through the use of what enzyme?

A

Glucose-6-phosphatase
G6P + H2O –> glucose + Pi

112
Q

True or false: Besides the liver, most other tissues lack G-6-phosphatase

A

True

113
Q

Principal rate limiting enzyme of glycolysis

A

Phosphofructokinase 1

114
Q

Most important regulatory point of glycolysis

A

Reaction 3 - Phosphofructokinase 1
First committed step of glycolysis

115
Q

2nd irreversible step of glycolysis

A

Reaction 3 - phosphofructokinase 1

116
Q

High ATP allosterically inhibits ____, lowering its affinity for ____

A

Phosphofructokinase 1; Fructose-6-P

117
Q

____ activates phosphofructokinase

A

AMP (becomes signal for low energy state)

118
Q

Inhibition of phosphofructokinase inhibits:

A

Hexokinase (concentration of fructose-6-P and glucose-6-P increase, which in turn inhibits hexokinase)

119
Q

G6P and F6P are in:

A

Equilibrium

120
Q

Formation of G3P involves:

A
  • 6 carbon sugar broken down into 2-3 C compounds (DHAP and G3P)
  • Isomerase used to convert DHAP into G3P
121
Q

1 molecule of glucose results in ___ molecules of G3P

A

2

122
Q

Formation of G3P to 1,3-Bisphosphoglycerate involves:

A

2 NAD+ to 2 NADH

123
Q

1,3-bisphosphoglycerate is converted to ____ through the enzyme ____. _____ is produced

A

3-phosphoglycerate; Phosphoglycerate Kinase; 2 ATP

124
Q

Reactions 8 and 9 function

A

rearrange 3-phosphoglycerate to high energy phosphate bond in phosphoenolpyruvate (PEP)

125
Q

3rd irreversible step of glycolysis

A

Formation of pyruvate through enzyme pyruvate kinase (takes off phosphate group from PEP)

126
Q

Formation of pyruvate yields ___ ATP

A

2

127
Q

_______ drives the whole series of glycolysis reactions to form pyruvate

A

Large release of free energy

128
Q

Pyruvate kinase is a ____ enzyme

A

Highly regulated

129
Q

Third regulated enzyme in glycolysis is ____. When glucose is abundant, ____ levels are high, and the enzyme is more ____. When ATP is abundant, the enzyme is ____

A

pyruvate kinase; insulin; active; inhibited

130
Q

Glycolysis irreversible steps

A
  1. hexokinase
  2. phosphofructokinase
  3. pyruvate kinase
131
Q

Glycolysis needs ___ to proceed

A

NAD+

132
Q

Gluconeogenesis definition

A

Re-synthesis of glucose from noncarbohydrate precursors

133
Q

Gluconeogenesis is or is not a reversal of glycolysis?

A

Is not!!

134
Q

Gluconeogenesis occurs in the

A

Cytoplasm

135
Q

Major site of gluconeogenesis

A

Liver

136
Q

Pyruvate carboxylase is found in the

A

Mitochondria

137
Q

Glucose-6-phosphatase is found in the

A

Membrane of ER (membrane bound enzyme)

138
Q

When is gluconeogenesis needed?

A

During fasting/starvation to maintain blood glucose

139
Q

___ needs glucose (specific organ)

A

Brain

140
Q

What are some non-carbohydrate precursors used for gluconeogenesis?

A
  • lactate (from muscle)
  • amino acids (from diet and breakdown of muscle)
  • Glycerol (hydrolysis of triglycerides)
141
Q

Conversion of pyruvate into PEP requires:

A

Biotin

142
Q

Phosphoenolpyruvate carboxykinase occurs in

A

Cytosol

143
Q

PEP carboxykinase is used for what reaction

A

To create PEP from Oxaloacetate

144
Q

Pyruvate carboxylase is used for what reaction

A

To create Oxaloacetate from Pyruvate

145
Q

PEP is a __ ___ compound

A

High energy

146
Q

Pyruvate to PEP: ATP used to ____ and it is removed to add ____

A

add carboxy group; P group

147
Q

Pyruvate to PEP: coupled ____ drives endergonic reactions

A

carboxylation/decarboxylation

148
Q

In gluconeogenesis, PEP is converted into ____ by the reversal of _____

A

Fructose-1,6-bisphosphate; glycolytic enzymes

149
Q

Formation of F6P is a ___ step and readily interconverts to _____

A

irreversible; G6P

150
Q

In gluconeogenesis, G6P is transported to _____, where it and Pi are transported back into the ____

A

lumen of ER; cytosol

151
Q
A

DEN 7101F - Human Structure and Function (23 decks)

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