II - Enzymes and Bioenergetics Flashcards
(163 cards)
1
Q
Protein catalysts that increase the velocity of a chemical reaction and are not consumed during the reaction they catalyze
A
Enzymes
2
Q
Physically distinct enzymes which catalyze the same reaction
A
Isozymes
3
Q
Catalyzes oxidations and reductions (transfers an electron from one molecule to another)
A
Dehydrogenase/Oxidoreductase
4
Q
Catalyzes transfer of moieties such as glucosyl,methyl or phosphoryl groups
A
Transferase
5
Q
Catalyzes hydrolytic cleavage of C-C, C-O, C-N and other bonds
A
Hydrolase
6
Q
Catalyzes hydrolytic cleavage of C-C, C-O, C-N and other bonds by atom elimination, leaving double bonds
A
Lyase
7
Q
Catalyzes geometric or structural changes within a molecule
A
Isomerase
8
Q
Catalyzes the joining together of two molecules coupled to the hydroolysis of ATP
A
Ligase
9
Q
Uses ATP to add high-energy phosphate onto a substrate
A
Kinase
10
Q
Adds inorganic phosphate onto a substrate without using ATP
A
Phosphorylase
11
Q
Removes a phosphate group from a substrate
A
Phosphatase
12
Q
Adds a hydroxyl group (-OH) onto a substrate
A
Hydroxylase
13
Q
Transfers CO2 groups with the help of biotin
A
Carboxylase
14
Q
Relocates a functional group within a molecule
A
Mutase
15
Q
Properties of Enzymes
A
contain an active site, efficient, specific, require cofactors, compartmentalized, regulated/inhibited
16
Q
Substrate fits into the preformed active site
A
Lock & Key Model
17
Q
Active site is slightly deformable to accomodate the shape of the substrate
A
Induced Fit Theory
18
Q
Apoenzyme + Cofactor
A
Holoenzyme
19
Q
Distinguished by their tight, stable incorporation into a protein’s structure by covalent or noncovalent forces
A
Prosthetic Groups
20
Q
Binds in a transient, dissociable manner either to the enzyme or to a substrate
A
Cofactor
21
Q
Serves as a recyclable shuttle (group transfer agent) that transports many substrates from their point of generation to teir point of utilization
A
Coenzyme
22
Q
Why are enzymes compartmentalized?
A
To protect from inhibitors and to promote a favorable environment
23
Q
Non-proteins required for enzyme function
A
Cofactors
24
Q
Organic Cofactors
A
Coenzymes
25
Not required for enzyme function but can alter the rate of reaction
Effectors
26
Enzymes lower _____.
free energy of activation
27
Enzymes _____ the energy of the reactants and products , and the equilibrium of the reaction.
do not change
28
Describes how reaction velocity varies with substrate concentration
Michaelis-Menten Equation
29
Vi = (Vmax[S]) / (Km + [S])
Michaelis-Menten Equation
30
Enzymes that follow Michaelis-Menten kinetics have a _____ curve.
hyperbolic
31
Allosteric reactions have a _____ curve.
sigmoid
32
Tells you how fast the reaction is
Vi
33
The maximum velocity or the maximal number of substrate molecules converted to products per unit time
Vmax
34
The substrate concentration where Vi = Vmax/2
Km
35
High Km =
Low Substrate Affinity
36
Low Km =
High Substrate Affinity
37
Above Km - ___-order kinetics, rate ___ [S]
zero-order kinetics, rate not affected by [S]
38
Below Km - ___-order kinetics, rate ___ [S]
first-order kinetics, rate directly proportional to [S]
39
Reciprocal of Michaelis-Menten Equation
Lineweaver-Burk Plot
40
Used to calculate Km and Vmax
Lineweaver-Burk Plot
41
Determines the mechanism of action of enzyme inhibitors
Lineweaver-Burk Plot
42
Any substance that can diminish te velocity of an enzyme-catalyzed reaction
Enzyme Inhibitor
43
Similar to substrate, competes for the binding site and reversibly attaches to the enzyme
Competitive Inhibitor
44
Competitive Inhibitor: reversed by increased ___, Km - ___, Vmax - ___
reversed by increased [S], Km - increased, Vmax - not changed
45
Irreversibly binds to the allosteric site of the enzyme and changes the conformation of the binding site
Non-competitive Inhibitor
46
Non-competitive Inhibitor: reversed by increased ___, Km - ___, Vmax - ___
reversed by increased [E], Km - not changed, Vmax - lowered
47
Regulation of Enzyme Activity: change in substrate concentration
immediate
48
Regulation of Enzyme Activity: allosteric binding sites
immediate
49
Regulation of Enzyme Activity: covalent modification
immediate to minutes
50
Regulation of Enzyme Activity: induction/repression of enzyme synthesis
hours-days
51
The substrate itself serves as an effector
Homotropic Effector
52
The effector is different from the substrate
Heterotropic Effector
53
Fed State: Phosphorylated or Dephosphorylated?
Dephosphorylated
54
Fasting State: Phosphorylated or Dephosphorylated?
Phosphorylated
55
Transfer and utilization of energy in biologic systems
Bioenergetics
56
Measure of the heat content of the reactants and products
Enthalpy (ΔH)
57
Enthalpy (ΔH) is measured in ____.
joules (J)
58
Endothermic
(+) ΔH - needs heat
59
Exothermic
(-) ΔH - releases heat
60
Measure of the change in randomness or disorder of the reactants and products
Entropy (ΔS)
61
Entropy (ΔS) is measured in ____.
joules/Kelvin (J/K)
62
Change in Free Energy
ΔG = ΔH - TΔS
63
Standard Free Energy Change: ΔG under _____ conditions, reactants and products are _____ each, T is _____, pressure is _____
standard conditions, 1 mole, 25°C or 298K, 1 atm
64
The natural tendency for processes is to proceed from a state of ___ energy to a state of ___ energy.
high to low
65
Net loss of energy (exergonic), spontaneous - ΔG _ 0
ΔG < 0
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Net gain of energy (endergonic), not spontaneous - ΔG _ 0
ΔG > 0
67
Equilibrium, forward reactions = backwards reactions - ΔG _ 0
ΔG = 0
68
(-) ΔH, (+) ΔS
spontaneous
69
(+) ΔH, (-) ΔS
not spontaneous
70
(+) ΔH, (+) ΔS
spontaneous at high T
71
(-) ΔH, (-) ΔS
spontaneous at low T
72
All ΔGs of a pathway are additive
Coupling Reactions
73
"Energy Currency/Cash" of the cell, transfers free energy derived from substances of higher energy potential to those of lower energy potential
ATP - adenosine triphosphate
74
ΔG of ATP → ADP + Pi
-7300 cal/mol or -7.3 kcal/mol
75
ATP Production: Phosphoenolpyruvate
creates ATP
76
ATP Production: Carbamoyl phosphate
creates ATP
77
ATP Production: 1,3-bisphosphoglycerate to 3-phosphoglycerate
creates ATP
78
ATP Production: Creatine phosphate
creates ATP
79
ATP Production: ADP → AMP + Pi
requires ATP
80
ATP Production: Pyrophosphate
made from ATP
81
ATP Production: Glucose 1-phosphate
made from ATP
82
ATP Production: Fructose 6-phosphate
made from ATP
83
ATP Production: AMP
made from ATP
84
ATP Production: Glucose 6-phosphate
made from ATP
85
ATP Production: Glycerol 3-phosphate
made from ATP
86
The greatest quantitative source of high energy phosphate in aerobic organisms
Oxidative Phosphorylation
87
Free energy comes from successive oxidation of substances in the respiratory chain within mitochondria
Oxidative Phosphorylation
88
The final substance to be reduced in oxidative phosphorylation
molecular oxygen
89
Loss of Electrons
Oxidation
90
Gain of Electrons
Reduction
91
Done through coupling reactions where a phosphate group is transferred to ADP from another substance with a higher ΔG°
Substrate Level Phosphorylation
92
"Bank" of the cell
ETC - Electron Transport Chain
93
"Cheques" of the cell
NAD+, FAD
94
Final common pathway by which electrons from different fuels of the body flow to oxygen
ETC - Electron Transport Chain
95
Electron carrier which produces 3 ATP
NAD+ - Nicotinamide Adenine Dinucleotide
96
Electron carrier which produces 2 ATP
FAD - Flavin Adenine Dinucleotide
97
Electron carrier derived from B3 (niacin)
NAD+ - Nicotinamide Adenine Dinucleotide
98
Electron carrier derived from B2 (riboflavin)
FAD - Flavin Adenine Dinucleotide
99
NAD+ is derived from _____.
B3 (niacin)
100
FAD is derived from _____.
B2 (riboflavin)
101
Mitochondria: freely permeable to most molecules
outer membrane
102
Mitochondria: impermeable to most molecules, selective
inner membrane
103
Mitochondria: folds in the inner membrane
cristae
104
Mitochondria: contains enzymes, mtDNA, mtRNA and mitchondrial enzymes
matrix
105
"Tellers" of the ETC "Bank"
complexes
106
Complex I
NADH Dehydrogenase
107
Complex II
Succinate Dehydrogenase, accepts FADH2, part of the Kreb's Cycle
108
Coenzyme Q
Ubiquinone, lipid, only non-protein part of the ETC
109
Complex III
Cytochrome b/c1 (Fe/heme protein)
110
Cytochrome c
Fe/heme protein, mobile part of the ETC
111
Complex IV
Cytochrome a/a3 (Cu/heme protein), where oxygen is reduced
112
Complex V
ATP Synthase
113
NADH Dehydrogenase
Complex I
114
Succinate Dehydrogenase, accepts FADH2, part of the Kreb's Cycle
Complex II
115
Ubiquinone, lipid, only non-protein part of the ETC
Coenzyme Q
116
Cytochrome b/c1 (Fe/heme protein)
Complex III
117
Fe/heme protein, mobile part of the ETC
Cytochrome c
118
Cytochrome a/a3 (Cu/heme protein), where oxygen is reduced
Complex IV
119
ATP Synthase
Complex V
120
Energy from oxidation of components in the respiratory chain is coupled to the translocation of hydrogen ions (H+/protons)
Mitchell's Chemiosmotic Theory
121
H= moves from inside to outside the inner mitochondrial membrane and accumulates in the intermembranous space
Mitchell's Chemiosmotic Theory
122
ETC generates an electrical gradient and a pH gradients across the inner mitochondrial membrane
Oxidative Phosphorylation
123
Oxidative Phosphorylation: intermembranous space is more _____
positive
124
Oxidative Phosphorylation: intermembranous space has ___ H+ ions
more
125
Oxidative Phosphorylation: protons are driven ___ the mitochondrial matrix
towards
126
Part of ATP Synthase that generates ATP from ADP and Pi
F1
127
Part of ATP Synthase that acts as a channel where protons pass through
F0
128
Anaerobic glycolysis is not enough for highly aerobic tissues like _____.
heart & nerves
129
Stops electron flow from substrate to oxygen
ETC Inhibitor
130
ETC Inhibitors: Barbiturate
Complex I
131
ETC Inhibitors: Piericidin A
Complex I
132
ETC Inhibitors: Amytal
Complex I
133
ETC Inhibitors: Rotenone
Complex I
134
ETC Inhibitors: Malonate
Complex II
135
ETC Inhibitors: Carboxin
Complex II
136
ETC Inhibitors: TTFA
Complex II
137
ETC Inhibitors: Antimycin A
Complex III
138
ETC Inhibitors: Dimercaprol
Complex III
139
ETC Inhibitors: Cyanide
Complex IV
140
ETC Inhibitors: Carbon monoxide (CO)
Complex IV
141
ETC Inhibitors: Sodium Azide
Complex IV
142
ETC Inhibitors: Hydrogen Sulfide
Complex IV
143
Increase the permeability of the inner mitochondrial membrane so proton gradient is lost (ATP synthesis stops but ETC continues and produces heat)
Uncouplers
144
Synthetic Uncouplers
2,4-dinitrophenol, aspirin
145
Uncoupler Protein
thermogenin (brown fat)
146
Directly inhibits Complex V so the proton gradient continues to rise but there is no escape valve for protons
ATP Synthase Inhibitors
147
Example of ATP Synthase Inhibitor
Oligomycin
148
Unstable products that are formed as byproducts of the ETC when molecular oxygen is partially reduced
Reactive Oxygen Species/Free Radicals: superoxide O2-, hydrogen peroxide H2O2, hydroxyl radical •HO
149
Produced by neutrophils to kill phagocytosed bacteria
Reactive Oxygen Species/Free Radicals
150
Increased during reperfusion injury due to the sudden burst of ETC activity with the introduction of oxygen
Reactive Oxygen Species/Free Radicals
151
Denatures and precipitates proteins and other substrates
Reactive Oxygen Species/Free Radicals
152
ROS Defense: Catalase
2H2O2 → 2H20 + O2
153
ROS Defense: Peroxidase
H2O2 + AH2→ 2H2O + A
154
ROS Defense: Superoxide Dismutase
2O2- + 2H+→ 2H2O + O2
155
2H2O2 → 2H20 + O2
Catalase
156
H2O2 + AH2→ 2H2O + A
Peroxidase
157
2O2- + 2H+→ 2H2O + O2
Superoxide Dismutase
158
Mitochondrial Diseases: Fatal Infantile Mitchondrial Myopathy
All Complexes
159
Mitochondrial Diseases: MELAS (Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes)
Complex I
160
Mitochondrial Diseases: Kearns-Sayre Syndrome
Complex II
161
Mitochondrial Diseases: Leber's Hereditary Optic Neuropathy
Complex III
162
Mitochondrial Diseases: Leigh's Disease
Complex IV
163
Mitochondrial Diseases: MERRF (Myoclonic Epilepsy with Ragged-Red Fibers)
Complex IV
