Enzymes Flashcards
(122 cards)
1
Q
Pretein catalysts that increase the velocity of chemical reactions and are NOT consumed in the reaction they catalyze
A
Ezymes
2
Q
_______ are physically distinct forms of given enzyme, each of which catalyze the same reaction
A
Isoenzymes
3
Q
Class of ezyme and example. Catalyze oxidation and reductions
A
Oxidoreductases
Eg lactate dhydrogenase
4
Q
Class of enzyme and example, catalyze transfer of moieties such as glucosyl, methyl, phosphoryl groups
A
Transferases
Eg methyl transferase
5
Q
Class of eznyme and example. Catalyze cleavage of C-C and C-O C-N and other bonds in the presence of water
A
Hydrolase
Eg urease
6
Q
Class of enzyme and example
Catalyze cleavage of C-O, CC, CN and other bonds by atom elimination, leaving double bonds
A
Lyases
Eg decarboxylase
7
Q
Class of ezyme and example
Catalyze geometric of stuctural changes within a molecule
A
Isomerases
Eg …mutas
8
Q
Class of enzyme and example
Catalyze joining together of 2 molecules coupled to the hydrolysis of ATP
A
Ligases
Eg carboxylases
9
Q
Enzymes contain active site for substrate held together by ______ bonds
A
Hydrogen
10
Q
T/F
Enzymes are highly specific and highly efficient
A
T
11
Q
Enzymes require _____, which bind in transient dissociable manner to either enzyme or substrate
A
Cofactor
12
Q
______ are substances that serve as recyclable shuttles or griupntransfer agents that transport many substrates from their point of generation to their point of utilization
A
Co-enzyme
13
Q
______ are distinguished by their tight stable incorporation into a protein stucture by covalent or noncovalent forces
A
Prosthetic groups
14
Q
_____ are non protein component of enzymes
A
Co factors
15
Q
Co-factor vs effector
Required for function
A
Co factor
16
Q
Co factor vs effector
Are not proteins like enzymes
Examples are Fe in Hgb, Cu in cytochrome oxidase
A
Co factor
17
Q
Co factor vs Effector
Negative______ will decrease rate of reaction
A
Effector
18
Q
Cofator vs effector
Positive ______ will increase rate of reaction
A
Effector
19
Q
Cofactor vs effector
Coezymes are organcic ______ like vitamins
A
Co factor
20
Q
Enzymes (increase/decrease) free energy of activation
A
Decrease
21
Q
Enymes (inc/dec/dont affect) the energy of the rectants and products, and the equilibrium ofnthe reaction
A
Dont affect
22
Q
Components of conjugated protein:
- Protein part
- Non-protein part
A
- Apoenzyme
2. Co factor
23
Q
Michaelis Menten Equation describes how reaction velocity varies with _______ concentratiom
A
Substrate
24
Q
3 assumptions of Michaelis Menten Equation
A
[S] is much greater than [ E]
[ES] is contant
[P] is low
25
Enzymes that follow Michaelis Menten kinetics have a (hyperbolic/sugmoidal/bell) curve
Hyperbolic
26
Vmax is
Maximal velocity
27
Maximal number of substrate molecules converted into product per unit time
Vmax
| Maximal Velocity
28
The substrate concentration at which Vi (initial velocity) is half the maximal velocity (Vmax/2) attainable at a particular concentration of enzyme
Km (Michaelis Constant)
29
3 factors that affect rate of reaction
Substrate concentration, Temperature, pH
30
Reciprocal of Michaelis -Menten equation
Lineweaver-Burk Plot
31
Used to calculate Km and Vmax as well as to determine the mechanism of action of enzyme inhibitors
Lineweaver-Burk Plot
32
Anysubstnace that can diminish the velocity if an enzyme catalyzed reaction
Enzyme inhibitor
33
Competititive/Noncompetitive inhibition
| Inhibitor is shaped like substrate and competes for binding site
Competitive
34
Competitive/Noncompetitive
| Reversed by increasing substrate concentration
Competitive
35
Competitive/noncompetitive
| Km is not changed
Non competitive
36
Competitive/noncompetitive
| Reversed by increasing enzyme concentration
Noncompetitive
37
Competitive/noncompetitive
| Vmax is not changed
Competitive
38
Competitive/Non-competitive
| Km is increased
Competitive
39
Competitive/Noncompetitive
| Vmax is lowered
Noncompetitive
40
Competitive/Noncompetitive
| Inhibitor binds to enzymes somewhere pther than the active site and halts catalysis
Noncompetitive
41
Competitive/noncompetitive
| Changes shape of enzyme so it cannot bind to substrate
Noncompetitive
42
T/F on enzyme regulation
The rates of most enzymes are responsive to changes in substrate comcentration, because the extracellular levels of many substrates is in the range of Km
F. Intracellular
43
T/F on enzyme regulation
| Heterotropic effectors: the substrate itself serves as an effector
F. Homotropic
44
T/F on enzyme synthesis
| Enzymes are often those that are needed only at one stage of development or under selected physiologic conditons
T
45
Identify enzyme
| Myocardial infaractiom
AST/ SGOT
46
Identify enzyme
| Viral hepatitis
ALT/SGPT
47
Identify enzyme
| Acute pancreatitis
Amylase
| Lipase
48
Identify enzyme
| Hepatocellular degeneration as in Wilsons dse
Ceruloplasmin
49
Identify enzyme
| Muscle disorders and MI
Creatine kinase
50
Identify enzyme
| Gauchers dse
B-glucocerebrosidase
51
Identify enzyme
| Bone diseases and obstructive liver dse
Alkaline phosphatase
52
Term that denotes transfer and utilization if energy in biologic systems
Bioenergetics
53
Measures the change in heat content of the reactants and products
Change in enthalpy (delta H)
54
Unit of measurement for enthalpy
Joules
55
Measures change of disorder of reactants and products
Change in entropy (delta S)
56
Unit of measurement for entropy
Joules per Kelvin
57
Energy available to do work
Change in free energy (delta G)
58
Predicts the direction in which a reaction will spontaneously proceed
Change in free energy (delta G)
59
Change in free energy apporaches this value as the reaction proceeds to equilibrium
Zero
60
Formula for change in free energy
DeltG= delta H - T delta S
61
Is the reaction spontaneous?
| Delta G < O
Yes
62
Is the reaction spomtaneous?
| Delta G = 0
Forward and backward rxns are equal
63
Is the rxn spontaneous?
| Delta G > 0
No, Endergonic, net gain of energy
64
Is the rxn spontaneous?
| Exergonic rxn
Yes (G<0) net loss of energy
65
T/F
| Endergonic processes proceed by coupling to exergonic processes
Coupling reactions
66
This molecule acts as energy currency of the cell, transferring free energy derived feom substances of higher energy to those of lower energy potential
ATP
67
Substrate level/Oxidative phosphorylation
| Done through coupling reactions where a phosphate group is transferred to ADP from another substance with higher delta G
Substrate level phosphorylation
68
Pathway wherein there is net formation of twoo high energy phosphates resulting from the formation of lactate from one molecule of glucose
Glycolysis
69
Two pathways that compose substrate level phosphorularylation
Glycolysis
| Citric acid cycle
70
Pathway wherein high energy phosphate is generated directly at the succinyl thiokinase step
Citric acid cycle
71
Pathway, greatest quantitative siurce of high energy phosphate in aerobic organism
Oxidative phosphorylation
72
Site of oxidative phosphosrylation
Mitochondria
73
Final substance to be reduced in oxidative phosphotylation
O2
74
Part of mitochondria
| Freely permeable to most molecules
Outer membranes
75
Part of mitochondria
| Impermeable to most substances
Inner membrane
76
Part of mitochondria
| Increases surface area
Cristae
77
Part of mitochondria
| Contains enzymes, mtDNA, mtRNA, mitochondrial ribosomes
Matrix
78
Final common pathway by which electrons from differents fuels of the body flow to oxygen
ETC
79
Location of ETC
Inner mitochondrial membrane
80
Two electron carriers used in ETC
NAD+, FAD
81
NAD+, FAD undergo ________ to form NADH and FADH2
Reduction
82
Vitamins from which these are derived:
1 )NADH
2)FADH2
1. B3 (niacin)
| 2. B2 (riboflavin)
83
The only 2 components of ETC not attached to inner mitochondrial membrane
Coenzyme Q, cytrochrome C
84
The only non protein compoenent of ETC
Ubiquinone (CoQ)
85
In ETC, protons are pumped to the intermembranous space in what complexes
I, III, IV
86
In ETC, final electron acceptor is
O2
87
This hypothesis explains how the free energy generated by the transport of electrons by ETC is used to produced ATP
Mitchell/Chemiosmotic hypothesis
88
T/F in ETC, the intramembranous space becomes more positive and has more H+
T
89
In ETC, protons reenter the mitochondrial matrix through what complex
ATP synthase complex (Complex V)
| -this is the oxidative phosphorylation part
90
T/F when there is lack of O2, there is decreased actovitynof ETC. ATP production shifts from oxidative phosphorylation to substrate level phosphorylation
T
91
Substrate level phosphorylation does not require oxygen but anaerobic glycolysis is not enough for highly aerobic tissues like _____ and _____
Neuron
| Cardiac muscle
92
Effects of ETC inhibitor (increase/decrease)
| O2 consumption
Decrease
93
Effects of ETC inhibitor (increase/decrease)
| Intracelluar NADH/NAD+ and FADH2/FAD ratio
Increase,
| NADH and FADH2 accumulate bcos they cannot transfer electrons to the ETC
94
Effects of ETC inhibitor (increase/decrease)
| ATP
Decrease
95
```
Identify 4 inhibitors
Complex I (NADH dehydrogenase)
```
Barbiturates
Piericidin A
Amytal
Rotenon
96
```
Identify 3 inhibitors
Complex II (Succinate-CoQ reductase)
```
Malonate
Carboxin
TTFA
97
```
Indentify 2 inhibitors
Complex III (CoQ-Cytochrome c reductase)
```
Antimycin A
| Dimercaprol
98
```
Identify 4 inhibitors
Complex IV (cytochrome oxidase)
```
Cyanide
Carbon monoxide
Sodium azide
Hydrogen sulfide
99
Compounds that increase permeability of inner mitochondiral membrane to protons
Uncouplers
100
In the presence of uncouplers, electron transport proceeds at (rapid/slow) rate without establishing a proton gradient
Rapid
101
Effect of uncouplers ETC
| Oxygen consumption
Increase
102
Effect of ETC uncoupler
| NADH/NAD+ and FADH2/FAD ratio
Decrease
| “Uncouplers are FADulous”
103
Effect of ETC uncoupler
| ATP synthesis
Decrease
104
2 examples of synthetic ETC uncoupler
2,4 dintrophenol
| Aspirin
105
Uncoupling ETC protein
Thermogenin (brown fats)
| Nenonates depend on this for heat production, prevention of hypothermia
106
Symptom if aspirin overdose caused by its ETC uncoupling property
Hyperpyrexia
107
Example of ATP synthase (complex V) inhibitor)
Oligomycin
108
T/F
In the presence of ATP synthase inhibitor, proton gradient continuous to rise but there is ni excape valve for the protons. ETC eventually stops sicne cytochromes can no longer pump protons into the intermembranous space
T
109
Substance that inhibits oxidative phosphorylationby inhibiting the transporter of ADP into and ATP out of the mitochondrion
Atractyloside
110
Unstable products produced as byproduct of ETC when molecular O2 is partially reduced
Reactive Oxygen Species:
Superoxide (O2-)
Hydrogen peroxide H2O2
Hydroxyl radical (OH-)
111
Increased during reperfusion injury, reacts with lipids to cause peroxidation to cause disruption of cell membranes, denatures & precipitates proteins and other substrates
Reactive Oxygen Species
112
Indentify enzyme
| Hydrogen peroxide —> water and O2
Catalase
113
Identify enzyme
| H2O2 + AH2 —> 2H2O + A
Peroxidase
114
Identify enzyme
| O2- + O2- +2H —> H2O2 + O2
Superoxide dismutase
115
T/F mitchondrial diseases follow Mendelian genetics
F. Non-Mendelian
116
```
Mitochondrial disease. Encephalomyopathy
Short stature
Stoke-like episodes
Migrainous headaches
Vomiting
Seizures
Lactic acidosis
```
MELAS - Mitochondrial Encephalomyelopathy, Lactic Acidosis, and Stroke-like episodes
117
Point mutations in mitochondrial DNA result to loss of retinal ganglion cell, leading to optic neuropathy and bilateral central vision loss
LHON ( Leber Hereditary Optic Neuropathy)
118
______ is the sum of all chamical reactions in a cell, tissue or whole body
Metabolism
119
Synthesis of compounds from smaller raw materials
Anabolism
120
T/F Anabolic pathways are exergonic and divergent processes
F, Endergonic
121
T/F Catabolic rxns are usually reductive
F, oxidative
122
Example of amphibolic reaction
Citric acid cycle (links anabolic and catabolic pathways)
