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ROS Flashcards

1
Q

Superoxide anion

A

1 extre electron
O2-

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1
Q

Peroxide

A

2 extra electrons
O2 2-

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2
Q

Hydroxyl radical

A

3 extra electrons, 1 H+
.OH

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3
Q

Hydroxyl ion

A

4 extra electrons
OH-

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4
Q

Hydrogen peroxide

A

1 extra electron, 2 H+
H2O2

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5
Q

What is the most potent ROS?

A

Hydroxyl radical

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6
Q

Hydroxyl radicals initiate reactions that form

A

Lipid peroxides and organic radicals

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7
Q

Which ROS is NOT a radical

A

H2O2

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8
Q

Superoxide is highly reactive but

A

Not soluble in lipids

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9
Q

How does superoxide generate radicals?

A

Reacts NONENZYMATICALLY with H2O2 in Haber-weiss reaction

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10
Q

Which ROS is lipid soluble

A

H2O2

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11
Q

What does H2O2 generate

A

Hydroxyl radicals at Fe2+ or Cu+ sites like ETC in mitochondira

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12
Q

What is the haber weiss reaction?

A

Superoxide (O2-) +Hydrogen peroxide (H2O2) = hydroxyl radical (.OH)

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13
Q

What is the fenton reactions

A

H2O2 gets close in proximity with Fu2+ or Cu+ in ETC, generates .OH hydroxyl radical and OH-

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14
Q

CoQ can carry

A

One electron and one proton OR
Two electrons and two protons

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15
Q

Oxidases, oxygenases, and peroxidases

A

Bind O2
Transfer single electrons via METAL

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16
Q

Free radical intermediate of oxidases, oxygenases, and peroxidases are

A

Released before reduction is complete

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17
Q

What enzyme is a source for free radicals being leaked

A

Cytochrome P450

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18
Q

What generates H2O2

A

Monoamine oxidase
Peroxisomal fatty acid oxidase

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19
Q

Ionization radiation can split

A

Water into .OH (hydroxyl radical) and H. (Hydrogen radical)

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20
Q

What initiates lipid peroxidation

A

Superoxide and hydroxyl

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21
Q

What does lipid peroxidation do

A

Makes lipids in membrane permeable, things can leak through

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22
Q

Increase in permeability causes

A

Influx of Ca2+ which damages mitochondria
Cellular swelling

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23
Q

Which AA gets oxidized and degraded

A

Cysteine

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24
Order of lipid peroxidation
Hydroxyl radical __> lipid radical --> lipid peroxy radical --> Lipid peroxide .OH--> L. --> Loo. ---> LOOH
25
Degradation of lipid generates
Malondialdehyde Indicates free radical damage, is a marker in blood
26
Chain reactions of lipid peroxidation can be terminated by
Vitamin E, tocopherol : Lipid soluble Vitamin C, ascorbate: water soluble
27
How does Vitamin E and C terminate lipid peroxidation
Donates one of their own electrons to correct the missing one and make it equally shared
28
What happens to proteins when hydroxyl radical attack happens
It fragments and the residues cross link with other residues
29
What can be used to estimate oxidative damage
8-hydroxyguanine because it is a fragmented and reformed protein caused from hydroxyl radical attack
30
At low concentrations NO functions as
Neurotransmitter and vasodilator
31
At high concentrations, NO
Combines with O2 or O2- to make RNOS
32
RNOS is involved with
Parkinsons, rheumatoid arthritis
33
nNos
Neuron nitric oxide synthase
34
eNOS
Endothelial neuron oxide synthase
35
iNOS
Inducible neuron oxide synthase
36
What is BH4
Terahydrobiopterin cofactor for NOS
37
Nitrogen dioxide is a free radical is caused by
Smoke inhalation Cigarettes
38
What does superoxide dismutase do
Takes a superoxide and turns it into hydrogen peroxide The H2O2 gets catalyzed by Fe2+ to make dangerous ROS like OH. and HOCl
39
What does NADPH do
Oxidizes with oxygen to make ROS on purpose. ROS is used to attack a bacteria
40
What uses NADPH
Macrophages and neutrophils use it to kill the bacteria
41
Defective superoxide dismutase causes
Lou gehrig's Disease Neurons stop working
42
What does superoxide dismutase do with two superoxides
1. Oxidizes with Cu2+ center and turns into O2 2. Reduces with Cu2+ center and turns into H2O2
43
What converts superoxides into O2 and H2O2
Cu2+
44
2 H2O2 goes to
2 H2O + O2
45
What enzyme turns the H2O2 from SOD into water and oxygen?
Catalase
46
What do antioxidants do
Donates one of their electrons to missing spot of free radical
47
Vitamin E is in
Membranes, lipid soluble
48
Cellular defenses against oxygen toxicity
Antioxidant defenses: donates electron to ROS Dietary oxidants Endogenous oxidants Cellular compartmentation: Separates ROS from rest of cell Metal sequestration: Metals (Fe+) bind to protein to prevent it from being used in Fenten Repair of cellular components
49
What is Cu+-Zn+ increased by
an increased superoxide
50
Three SOD isoenzymes
Cu+-Zn2+ in cytosol Cu+-Zn2+ in extracellular compartment Mn2+ in mitochondria
51
What type of enzyme is SOD, catalase, gluathione reductase, and glutathione peroxidase
Antioxidant scavenging enzymes
52
Isoflavin gives protection against
Osteoporosis Heart disease Breast cancer
53
Endogenous antioxidants
Uric acid Melatonin
54
What enzyme can induce parkinsons
Rotenone
55
What reduces dopamin release
Monoamine oxidase (MAO)
56
What does glutathione peroxidase do
Converts 2GSH to GSSG Oxidizes GSH to GSSG Converts 2H2O to 2H2O + O2
57
What does glutathione reductase do
Reduces GSSG to GSH Makes NADP+ from NADPH which comes from pentose pathway
58
What is GSH
Glutathione (with sulfhydryl bond)
59
What is GSSG
Glutathione disulfide
60
Vitamin E does what reaction to radicals
Reduction
61
Vitamin C does what reaction to radicals
Reduction
62
What is vitamin C rich in
Citrus fruits
63
What is vitamin E rich in
Legumes, nuts
64
Catalase is found in
Peroxisomes

Biochemistry (13 decks)

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