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Biochemistry by mgcMD > Enzymes > Flashcards

Enzymes Flashcards

1
Q

Pretein catalysts that increase the velocity of chemical reactions and are NOT consumed in the reaction they catalyze

A

Ezymes

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2
Q

_______ are physically distinct forms of given enzyme, each of which catalyze the same reaction

A

Isoenzymes

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3
Q

Class of ezyme and example. Catalyze oxidation and reductions

A

Oxidoreductases

Eg lactate dhydrogenase

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4
Q

Class of enzyme and example, catalyze transfer of moieties such as glucosyl, methyl, phosphoryl groups

A

Transferases

Eg methyl transferase

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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

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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

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7
Q

Class of ezyme and example

Catalyze geometric of stuctural changes within a molecule

A

Isomerases

Eg …mutas

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8
Q

Class of enzyme and example

Catalyze joining together of 2 molecules coupled to the hydrolysis of ATP

A

Ligases

Eg carboxylases

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9
Q

Enzymes contain active site for substrate held together by ______ bonds

A

Hydrogen

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10
Q

T/F

Enzymes are highly specific and highly efficient

A

T

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11
Q

Enzymes require _____, which bind in transient dissociable manner to either enzyme or substrate

A

Cofactor

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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

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13
Q

______ are distinguished by their tight stable incorporation into a protein stucture by covalent or noncovalent forces

A

Prosthetic groups

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14
Q

_____ are non protein component of enzymes

A

Co factors

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15
Q

Co-factor vs effector

Required for function

A

Co factor

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16
Q

Co factor vs effector
Are not proteins like enzymes
Examples are Fe in Hgb, Cu in cytochrome oxidase

A

Co factor

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17
Q

Co factor vs Effector

Negative______ will decrease rate of reaction

A

Effector

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18
Q

Cofator vs effector

Positive ______ will increase rate of reaction

A

Effector

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19
Q

Cofactor vs effector

Coezymes are organcic ______ like vitamins

A

Co factor

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20
Q

Enzymes (increase/decrease) free energy of activation

A

Decrease

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21
Q

Enymes (inc/dec/dont affect) the energy of the rectants and products, and the equilibrium ofnthe reaction

A

Dont affect

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22
Q

Components of conjugated protein:

  1. Protein part
  2. Non-protein part
A
  1. Apoenzyme

2. Co factor

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23
Q

Michaelis Menten Equation describes how reaction velocity varies with _______ concentratiom

A

Substrate

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24
Q

3 assumptions of Michaelis Menten Equation

A

[S] is much greater than [ E]
[ES] is contant
[P] is low

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25
Q

Enzymes that follow Michaelis Menten kinetics have a (hyperbolic/sugmoidal/bell) curve

A

Hyperbolic

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26
Q

Vmax is

A

Maximal velocity

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27
Q

Maximal number of substrate molecules converted into product per unit time

A

Vmax

Maximal Velocity

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28
Q

The substrate concentration at which Vi (initial velocity) is half the maximal velocity (Vmax/2) attainable at a particular concentration of enzyme

A

Km (Michaelis Constant)

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29
Q

3 factors that affect rate of reaction

A

Substrate concentration, Temperature, pH

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30
Q

Reciprocal of Michaelis -Menten equation

A

Lineweaver-Burk Plot

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31
Q

Used to calculate Km and Vmax as well as to determine the mechanism of action of enzyme inhibitors

A

Lineweaver-Burk Plot

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32
Q

Anysubstnace that can diminish the velocity if an enzyme catalyzed reaction

A

Enzyme inhibitor

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33
Q

Competititive/Noncompetitive inhibition

Inhibitor is shaped like substrate and competes for binding site

A

Competitive

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34
Q

Competitive/Noncompetitive

Reversed by increasing substrate concentration

A

Competitive

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35
Q

Competitive/noncompetitive

Km is not changed

A

Non competitive

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36
Q

Competitive/noncompetitive

Reversed by increasing enzyme concentration

A

Noncompetitive

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37
Q

Competitive/noncompetitive

Vmax is not changed

A

Competitive

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38
Q

Competitive/Non-competitive

Km is increased

A

Competitive

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39
Q

Competitive/Noncompetitive

Vmax is lowered

A

Noncompetitive

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40
Q

Competitive/Noncompetitive

Inhibitor binds to enzymes somewhere pther than the active site and halts catalysis

A

Noncompetitive

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41
Q

Competitive/noncompetitive

Changes shape of enzyme so it cannot bind to substrate

A

Noncompetitive

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42
Q

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

A

F. Intracellular

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43
Q

T/F on enzyme regulation

Heterotropic effectors: the substrate itself serves as an effector

A

F. Homotropic

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44
Q

T/F on enzyme synthesis

Enzymes are often those that are needed only at one stage of development or under selected physiologic conditons

A

T

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45
Q

Identify enzyme

Myocardial infaractiom

A

AST/ SGOT

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46
Q

Identify enzyme

Viral hepatitis

A

ALT/SGPT

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47
Q

Identify enzyme

Acute pancreatitis

A

Amylase

Lipase

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48
Q

Identify enzyme

Hepatocellular degeneration as in Wilsons dse

A

Ceruloplasmin

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49
Q

Identify enzyme

Muscle disorders and MI

A

Creatine kinase

50
Q

Identify enzyme

Gauchers dse

A

B-glucocerebrosidase

51
Q

Identify enzyme

Bone diseases and obstructive liver dse

A

Alkaline phosphatase

52
Q

Term that denotes transfer and utilization if energy in biologic systems

A

Bioenergetics

53
Q

Measures the change in heat content of the reactants and products

A

Change in enthalpy (delta H)

54
Q

Unit of measurement for enthalpy

55
Q

Measures change of disorder of reactants and products

A

Change in entropy (delta S)

56
Q

Unit of measurement for entropy

A

Joules per Kelvin

57
Q

Energy available to do work

A

Change in free energy (delta G)

58
Q

Predicts the direction in which a reaction will spontaneously proceed

A

Change in free energy (delta G)

59
Q

Change in free energy apporaches this value as the reaction proceeds to equilibrium

60
Q

Formula for change in free energy

A

DeltG= delta H - T delta S

61
Q

Is the reaction spontaneous?

Delta G < O

62
Q

Is the reaction spomtaneous?

Delta G = 0

A

Forward and backward rxns are equal

63
Q

Is the rxn spontaneous?

Delta G > 0

A

No, Endergonic, net gain of energy

64
Q

Is the rxn spontaneous?

Exergonic rxn

A

Yes (G<0) net loss of energy

65
Q

T/F

Endergonic processes proceed by coupling to exergonic processes

A

Coupling reactions

66
Q

This molecule acts as energy currency of the cell, transferring free energy derived feom substances of higher energy to those of lower energy potential

67
Q

Substrate level/Oxidative phosphorylation

Done through coupling reactions where a phosphate group is transferred to ADP from another substance with higher delta G

A

Substrate level phosphorylation

68
Q

Pathway wherein there is net formation of twoo high energy phosphates resulting from the formation of lactate from one molecule of glucose

A

Glycolysis

69
Q

Two pathways that compose substrate level phosphorularylation

A

Glycolysis

Citric acid cycle

70
Q

Pathway wherein high energy phosphate is generated directly at the succinyl thiokinase step

A

Citric acid cycle

71
Q

Pathway, greatest quantitative siurce of high energy phosphate in aerobic organism

A

Oxidative phosphorylation

72
Q

Site of oxidative phosphosrylation

A

Mitochondria

73
Q

Final substance to be reduced in oxidative phosphotylation

74
Q

Part of mitochondria

Freely permeable to most molecules

A

Outer membranes

75
Q

Part of mitochondria

Impermeable to most substances

A

Inner membrane

76
Q

Part of mitochondria

Increases surface area

77
Q

Part of mitochondria

Contains enzymes, mtDNA, mtRNA, mitochondrial ribosomes

78
Q

Final common pathway by which electrons from differents fuels of the body flow to oxygen

79
Q

Location of ETC

A

Inner mitochondrial membrane

80
Q

Two electron carriers used in ETC

81
Q

NAD+, FAD undergo ________ to form NADH and FADH2

82
Q

Vitamins from which these are derived:
1 )NADH
2)FADH2

A
  1. B3 (niacin)

2. B2 (riboflavin)

83
Q

The only 2 components of ETC not attached to inner mitochondrial membrane

A

Coenzyme Q, cytrochrome C

84
Q

The only non protein compoenent of ETC

A

Ubiquinone (CoQ)

85
Q

In ETC, protons are pumped to the intermembranous space in what complexes

A

I, III, IV

86
Q

In ETC, final electron acceptor is

87
Q

This hypothesis explains how the free energy generated by the transport of electrons by ETC is used to produced ATP

A

Mitchell/Chemiosmotic hypothesis

88
Q

T/F in ETC, the intramembranous space becomes more positive and has more H+

89
Q

In ETC, protons reenter the mitochondrial matrix through what complex

A

ATP synthase complex (Complex V)

-this is the oxidative phosphorylation part

90
Q

T/F when there is lack of O2, there is decreased actovitynof ETC. ATP production shifts from oxidative phosphorylation to substrate level phosphorylation

91
Q

Substrate level phosphorylation does not require oxygen but anaerobic glycolysis is not enough for highly aerobic tissues like _____ and _____

A

Neuron

Cardiac muscle

92
Q

Effects of ETC inhibitor (increase/decrease)

O2 consumption

93
Q

Effects of ETC inhibitor (increase/decrease)

Intracelluar NADH/NAD+ and FADH2/FAD ratio

A

Increase,

NADH and FADH2 accumulate bcos they cannot transfer electrons to the ETC

94
Q

Effects of ETC inhibitor (increase/decrease)

ATP

95
Q 
Identify 4 inhibitors
Complex I (NADH dehydrogenase)
A

Barbiturates
Piericidin A
Amytal
Rotenon

96
Q 
Identify 3 inhibitors
Complex II (Succinate-CoQ reductase)
A

Malonate
Carboxin
TTFA

97
Q 
Indentify 2 inhibitors
Complex III (CoQ-Cytochrome c reductase)
A

Antimycin A

Dimercaprol

98
Q 
Identify 4 inhibitors
Complex IV (cytochrome oxidase)
A

Cyanide
Carbon monoxide
Sodium azide
Hydrogen sulfide

99
Q

Compounds that increase permeability of inner mitochondiral membrane to protons

A

Uncouplers

100
Q

In the presence of uncouplers, electron transport proceeds at (rapid/slow) rate without establishing a proton gradient

101
Q

Effect of uncouplers ETC

Oxygen consumption

102
Q

Effect of ETC uncoupler

NADH/NAD+ and FADH2/FAD ratio

A

Decrease

“Uncouplers are FADulous”

103
Q

Effect of ETC uncoupler

ATP synthesis

104
Q

2 examples of synthetic ETC uncoupler

A

2,4 dintrophenol

Aspirin

105
Q

Uncoupling ETC protein

A

Thermogenin (brown fats)

Nenonates depend on this for heat production, prevention of hypothermia

106
Q

Symptom if aspirin overdose caused by its ETC uncoupling property

A

Hyperpyrexia

107
Q

Example of ATP synthase (complex V) inhibitor)

A

Oligomycin

108
Q

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

109
Q

Substance that inhibits oxidative phosphorylationby inhibiting the transporter of ADP into and ATP out of the mitochondrion

A

Atractyloside

110
Q

Unstable products produced as byproduct of ETC when molecular O2 is partially reduced

A

Reactive Oxygen Species:
Superoxide (O2-)
Hydrogen peroxide H2O2
Hydroxyl radical (OH-)

111
Q

Increased during reperfusion injury, reacts with lipids to cause peroxidation to cause disruption of cell membranes, denatures & precipitates proteins and other substrates

A

Reactive Oxygen Species

112
Q

Indentify enzyme

Hydrogen peroxide —> water and O2

113
Q

Identify enzyme

H2O2 + AH2 —> 2H2O + A

A

Peroxidase

114
Q

Identify enzyme

O2- + O2- +2H —> H2O2 + O2

A

Superoxide dismutase

115
Q

T/F mitchondrial diseases follow Mendelian genetics

A

F. Non-Mendelian

116
Q 
Mitochondrial disease. Encephalomyopathy
Short stature
Stoke-like episodes
Migrainous headaches
Vomiting
Seizures
Lactic acidosis
A

MELAS - Mitochondrial Encephalomyelopathy, Lactic Acidosis, and Stroke-like episodes

117
Q

Point mutations in mitochondrial DNA result to loss of retinal ganglion cell, leading to optic neuropathy and bilateral central vision loss

A

LHON ( Leber Hereditary Optic Neuropathy)

118
Q

______ is the sum of all chamical reactions in a cell, tissue or whole body

A

Metabolism

119
Q

Synthesis of compounds from smaller raw materials

120
Q

T/F Anabolic pathways are exergonic and divergent processes

A

F, Endergonic

121
Q

T/F Catabolic rxns are usually reductive

A

F, oxidative

122
Q

Example of amphibolic reaction

A

Citric acid cycle (links anabolic and catabolic pathways)

Biochemistry by mgcMD (19 decks)

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