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
2
Q
Cells extract energy from:
A
- food
- energy stores
3
Q
Catabolism: releases or requires energy?
A
Releases energy
4
Q
Anabolism: releases or requires energy?
A
Requires energy
5
Q
Catabolism
A
Degradation of larger molecules into smaller ones
6
Q
Anabolism
A
Conversion of monomers into polymers of more complex molecules
7
Q
Catabolism - overall reaction
A
Fuel (carbohydrates, fats) –> CO2 + H2O + useful energy
8
Q
Catabolism involves metabolic reactions that _____ energy through the use of simple organic compounds. Most involve _____
A
Yield energy; oxidative degradation
9
Q
Oxidation means
A
Loss of electrons
10
Q
Degradation is also known as
A
Catabolism
11
Q
Biosynthetic is also known as
A
Anabolism
12
Q
Anabolism overall reaction
A
Useful energy + simple precursors –> complex molecules
13
Q
Anabolism involves metabolic reactions that ____ and _____. Most involve ____ biosynthesis
A
use energy and create macromolecules; reductive
14
Q
Reduction is
A
gain of electrons
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
16
Q
Synthetic reactions are found in the:
A
Cytosol
17
Q
Oxidation reactions are found in the:
A
Mitochondria
18
Q
General principles of metabolism (3)
A
- fuels are degraded, large molecules are constructed through step by step metabolic pathways
- Common energy currency (ATP) links energy-releasing pathways with energy requiring pathways
- Oxidation of carbon fuels powers formation of ATP
19
Q
In metabolism, there is a highly integrated network of over 1000 chemical reactions, but there are 4 common motifs, which are:
A
- energy currency
- limited number of activated intermediates
- types of reactions is small
- regulated in common ways
20
Q
___ molecules play a central role in metabolism
A
100
21
Q
What types of chemical reactions are found in metabolism?
A
- Oxidation-reduction
- Ligation requiring ATP cleavage (forms covalent bonds)
- Isomerization
- Group transfer
- Hydrolytic
- Additional or removal of functional groups
22
Q
Methods of regulation of metabolic reactions
A
- amount of enzymes
- enzymes catalytic activity
- accessibility of substrate
23
Q
The amount of enzymes is controlled by
A
Rate of synthesis, rate of degradation
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
25
Accessibility of substrate is controlled by:
- compartmentation which separates opposing reactions
- control of flux of substrates
26
Reaction can only occur spontaneously if:
ΔG is negative
27
Metabolic pathways can couple _____
Individual reactions
28
Two criteria for coupling individual reactions
- reactions must be specific
- sum of reactions must be thermodynamically favorable (-ΔG)
29
What do coupled reactions share?
Same intermediate (product of one reaction is the reactant for the next)
30
A thermodynamically unfavorable reaction is driven by:
a favorable reaction
(reactions are coupled by shared intermediate)
31
Examples of special molecules that act as carriers between metabolic reactions
- ATP
- NADH/NADPH
- FADH2
- Coenzyme A
- Biotin
- Tetrahydrofolate
- S-Adenosylmethionine
- Uridine Diphosphate glucose
32
Phosphoryl group is carried by
ATP
Phosphoenolpyruvate (PEP, high energy)
33
Electrons are carried by
- NADH
- NADPH
- FADH2
34
Acyl group is carried by
Coenzyme A
35
CO2 group is carried by
Biotin
36
One-carbon units are carried by
Tetrahydrofolate
37
Methyl groups are carried by
S-adenosylmethionine
38
Glucose group is carried by
Uridine Diphosphate Glucose
39
____ are unifying motifs of biochemistry
Carrier molecules (ATP most familiar)
40
What is the universal energy carrier?
ATP
41
What process produces free energy (ATP)?
Oxidative degradation
42
Energy stored in ATP is conserved via:
High energy chemical bonds
43
ATP is a ____ made of ____
Nucleotide; adenine, ribose, triphosphate
44
ATP contains ____ phosphoanhydride bonds
2
45
True or false: ATP stores energy transiently to do work
True - transient store of energy, made and degraded over and over again
46
Phosphoanhydride bond is a type of:
Covalent bond
47
High energy phosphoanhydride bond is formed via:
- condensation of 2 molecules of phosphate (PO43-)
- subsequent loss of water (condensation reaction)
48
When phosphoanhydride bonds are broken, ____ is released
Large amounts of energy
49
Principle immediate donor of free energy
ATP
50
True or false: ATP serves as storage of free energy
False - does not; ATP turnover is high and must be continuously regenerated from ADP
51
A highly favorable reaction has:
A large change in free energy
52
An energy-yielding reaction results in:
Synthesis of ATP
53
An energy-requiring reactions uses ____
ATP
54
Examples of energy-requiring reactions
- performance of mechanical work (muscle contraction, cellular movements)
- active transport of molecules and ions
- synthesis of macromolecules from simple precursors
55
Fundamental mode of energy exchange
ATP-ADP cycle
56
____ can drive unfavorable reactions
ATP hydrolysis
57
ATP hydrolysis can change the equilibrium ratio of products to reactants by
10^5 (reaction by itself compared to coupled with ATP hydrolysis)
58
True or false: ATP is the only carrier of phosphoryl groups
False - there are many others (phosphoenolpyruvate, creatine phosphate, pyrophosphate, etc.)
59
Phosphoryl-transfer potential is an important form of:
Energy conversion
60
ATP is a phosphate ____
Donor
61
ADP is a phosphate ____
Acceptor
62
ATP to ADP free energy number
- 7.3
63
Phosphoenolpyruvate free energy number
- 14.8
64
How does phosphoenolpyruvate help create ATP?
transfers phosphoryl group to ADP in breakdown of glucose
65
Creatine phosphate is used in _____ and serves as:
muscle; reservoir of high energy phosphoryl groups that can be transferred to ADP
66
Many activated carriers are derived from _____
water-soluble vitamins
67
NADH/NADPH are derived from what vitamin?
Nicotinate (niacin) B3
68
FADH2 is derived from what vitamin?
Riboflavin (vitamin B2)
69
Coenzyme A is derived from what vitamin?
Pantothenate B5
70
Tetrahydrofolate is derived from what vitamin?
Folate
71
NADH and FADH2 are major electron carriers in the _____
oxidation of fuels
72
NADH and FADH2 are used during
- oxidation glucose and fatty acids
- electrons transferred using these carrier molecules
73
NAD+ stands for
Nicotinamide adenine dinucleotide
73
Under aerobic conditions, the ultimate electron acceptor is:
O2
74
NAD+ is a
pyridine dinucleotide
75
FAD stands for
Flavin adenine dinucleotide
76
FAD is a ___ compound
Flavin
77
The reactive part of NAD+ is:
Nicotinamide ring
78
In NAD+, the pyridine derivative is synthesized from:
niacin (B3)
79
NAD+ accepts ____ and ____
1 hydrogen ion; 2 electrons
80
Reduced form of NAD+/function?
NADH; passes electrons to oxygen
81
Reaction with NAD+ is called:
Dehydrogenation reaction
82
Where is the reactive site of FAD?
Flavin ring (on nitrogens where hydrogens can be accepted)
83
FAD contains what kind of bond?
Phosphoanhydride bond (1)
84
Structure of the oxidized form of FAD contains:
- FMN unit (flavin mononucleotide)
- AMP unit
85
When FAD is reduced, it accepts:
- 2 electrons
- 2 hydrogen ions
86
What is the difference between NAD+ and NADP+?
- 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
With NADPH, ____ is needed in addition to ATP
reducing power
88
Coenzyme A reactive group?
terminal sulfhydryl
89
Coenzyme A transfers ____ groups in many _____ reactions
acyl groups; enzyme-catalyzed acylation reactions
90
Acyl CoA and Acetyl CoA have an _____ which has potential for
activated acetyl group; high acetyl group transfer potentialIn
91
In Coenzyme A, what is found on the 3' end?
3'-Phospho-ADP
92
Acyl CoA and Acetyl CoA have what kind of bond?
Thioester bond
93
Stages in the extraction of energy from food (3)
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
Vast majority of ATP is formed via
Oxidative phosphorylation
95
Stages in glucose oxidation (4)
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
Where does glycolysis occur?
In the cytosol
97
Net products of glycolysis
- 2 ATP
- 2 NADH
- 2 Pyruvate
98
All glycolysis intermediates are:
Water soluble, phosphorylated molecules
99
Stage 1 of glycolysis involves _____, and Stage 2 of glycolysis involves _____
trapping glucose in cell; harvesting a small amount of ATP to produce pyruvate
100
____ traps glucose
Hexokinase
101
1st irreversible step of glycolysis
Glucose is phosphorylated by hexokinase
102
Hexokinase is inhibited by:
G6P
103
Hexokinase Km
0.2 mmol/L
104
Hexokinase has a ____ affinity for its substrate (glucose)
High
105
Glucokinase
Special liver form of hexokinase enzyme
106
Glucokinase Km
10 mmol/L
107
Is glucokinase feedback regulated?
No
108
High glucose levels drive the formation of:
Glycogen (storage of glucose)
109
Glucokinase has a ____ affinity for its substrate (glucose)
Low (high Km)
110
Km has a direct/reciprocal relationship with substrate affinity?
Reciprocal - High Km = low affinity for substrate
111
Liver maintains blood glucose through the use of what enzyme?
Glucose-6-phosphatase
G6P + H2O --> glucose + Pi
112
True or false: Besides the liver, most other tissues lack G-6-phosphatase
True
113
Principal rate limiting enzyme of glycolysis
Phosphofructokinase 1
114
Most important regulatory point of glycolysis
Reaction 3 - Phosphofructokinase 1
First committed step of glycolysis
115
2nd irreversible step of glycolysis
Reaction 3 - phosphofructokinase 1
116
High ATP allosterically inhibits ____, lowering its affinity for ____
Phosphofructokinase 1; Fructose-6-P
117
____ activates phosphofructokinase
AMP (becomes signal for low energy state)
118
Inhibition of phosphofructokinase inhibits:
Hexokinase (concentration of fructose-6-P and glucose-6-P increase, which in turn inhibits hexokinase)
119
G6P and F6P are in:
Equilibrium
120
Formation of G3P involves:
- 6 carbon sugar broken down into 2-3 C compounds (DHAP and G3P)
- Isomerase used to convert DHAP into G3P
121
1 molecule of glucose results in ___ molecules of G3P
2
122
Formation of G3P to 1,3-Bisphosphoglycerate involves:
2 NAD+ to 2 NADH
123
1,3-bisphosphoglycerate is converted to ____ through the enzyme ____. _____ is produced
3-phosphoglycerate; Phosphoglycerate Kinase; 2 ATP
124
Reactions 8 and 9 function
rearrange 3-phosphoglycerate to high energy phosphate bond in phosphoenolpyruvate (PEP)
125
3rd irreversible step of glycolysis
Formation of pyruvate through enzyme pyruvate kinase (takes off phosphate group from PEP)
126
Formation of pyruvate yields ___ ATP
2
127
_______ drives the whole series of glycolysis reactions to form pyruvate
Large release of free energy
128
Pyruvate kinase is a ____ enzyme
Highly regulated
129
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 ____
pyruvate kinase; insulin; active; inhibited
130
Glycolysis irreversible steps
1. hexokinase
2. phosphofructokinase
3. pyruvate kinase
131
Glycolysis needs ___ to proceed
NAD+
132
Gluconeogenesis definition
Re-synthesis of glucose from noncarbohydrate precursors
133
Gluconeogenesis is or is not a reversal of glycolysis?
Is not!!
134
Gluconeogenesis occurs in the
Cytoplasm
135
Major site of gluconeogenesis
Liver
136
Pyruvate carboxylase is found in the
Mitochondria
137
Glucose-6-phosphatase is found in the
Membrane of ER (membrane bound enzyme)
138
When is gluconeogenesis needed?
During fasting/starvation to maintain blood glucose
139
___ needs glucose (specific organ)
Brain
140
What are some non-carbohydrate precursors used for gluconeogenesis?
- lactate (from muscle)
- amino acids (from diet and breakdown of muscle)
- Glycerol (hydrolysis of triglycerides)
141
Conversion of pyruvate into PEP requires:
Biotin
142
Phosphoenolpyruvate carboxykinase occurs in
Cytosol
143
PEP carboxykinase is used for what reaction
To create PEP from Oxaloacetate
144
Pyruvate carboxylase is used for what reaction
To create Oxaloacetate from Pyruvate
145
PEP is a __ ___ compound
High energy
146
Pyruvate to PEP: ATP used to ____ and it is removed to add ____
add carboxy group; P group
147
Pyruvate to PEP: coupled ____ drives endergonic reactions
carboxylation/decarboxylation
148
In gluconeogenesis, PEP is converted into ____ by the reversal of _____
Fructose-1,6-bisphosphate; glycolytic enzymes
149
Formation of F6P is a ___ step and readily interconverts to _____
irreversible; G6P
150
In gluconeogenesis, G6P is transported to _____, where it and Pi are transported back into the ____
lumen of ER; cytosol
151
