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Biochemistry 2 > Oxygen Toxicity > Flashcards

Oxygen Toxicity Flashcards

0
Q

______ is probably the most potent ROS

A

Hydroxy radical

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1
Q

When O2 accepts single electrons, it is transformed into highly reactive ________ that demage cellular lipids, proteins and DNA

A

Oxygen radicals

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2
Q

One oxygen molecule can accept up to ______ electrons, generating __________

A

4
Superoxide, hydrogen peroxide
Hydroxyl radical, water

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3
Q

Hydrogen peroxide is not a radical but a ______ because it can generate hydroxyl radical

A

ROS

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4
Q

Transition metals, such as Fe2+ or Cu+, catalyze formation of the _______ from _____ in he non-enzymatic Fenton reaction

A

hydroxyl radicals

hydrogen peroxide

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5
Q

under physiological conditions, ____ are sequestered to reduce Fenton reaction. However, _____ can expose such metals to allow secondary free radical injury

A

transition metals

Injury

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6
Q

RNOS contain both nitrogen and oxygen and derive principally from the free radical ________

A

Nitric oxide (NO)

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7
Q

Free radical nitric oxide is produced endogenously by enzyme _______

A

Nitric oxide synthase (NOS)

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8
Q

One of the major sites of superoxide generation is ________ in the mitochondria electron transport chain

A

Coenzyme Q (CoQ)

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9
Q

The _______ form of CoQ can accidentally transfer an electron to dissolved O2, thereby forming _______

A

One-electron reduced

Superoxide

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10
Q

Name 3 enzyme in the cell that bind O2 and transfer single electron to it via a metal

A

Oxidase
Peroxidase
Oxygenase

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11
Q

_______ enzymes are a major source of free radical leakage

A

Cytochrome P450

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12
Q

Induction of cytochrome P450 enzyme by ____, ____ or ____ leads to increased cellular injury

A

Alcohol
Drug
Chemical toxicant

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13
Q

_____ and _____ are generated enzymatically as major reaction products by several oxidase present in peroxisome

A

Hydrogen peroxide

Lipid peroxide

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14
Q

Peroxisomal ________ generates hydrogen peroxide

A

Fatty acyl-CoA oxidase

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15
Q

Lipid peroxidase are formed enzymatically as intermediate in the pathway of many ______, including leukotrienes and prostaglandin

A

Eicosanoids

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16
Q

Ionizing radiation has a high energy level that it can split water into ___ and ____.

A

Hydroxyl

Hydrogen radical

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17
Q

Ionizing radiation can generate organic radical through direct collision with ______

A

Organic cellular component

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18
Q

______ that form lipid peroxyl radical and lipid peroxide make a major contribution to ____ -induced injury

A

Chain reaction

ROS

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19
Q

Initiator free radical, such as _______, begins chain reaction by extract a hydrogen atom from the double bond of _______ in membrane lipids

A

Hydroxyl radical

Polyunsaturated fatty acid

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20
Q

After extraction of hydrogen atom from fatty acid, the chain reaction is propagated when ______ adds to form _____ and _____.

A

O2
Lipid peroxyl radial
Lipid peroxide

21
Q

Disruption of membrane integrity of membrane attack may result in further ______

A

Free radical production

22
Q

_____ of lipid molecules can cause lipid degradation

A

Peroxidation

23
Q

_____ formed from lipid peroxidation can _____ proteins

A

Aldehyde

Cross-link

24
Q

As a result of oxidative damage, protein may cause _______, _____ and ______

A

Fragmentation
Crosslinking
Aggregation

25
Q

Oxidation of cysteine sulfhydryl group of _______ compromise the cellular defense against free radical injury.

A

Glutathione

26
Q

Oxygen derived free radical can cause ______ in DNA and also cause ______ backbone breakage

A

Base alteration

Deoxyribose

27
Q

Nitric Oxide (NO) has a single electron and hence is ______

A

Free radical

28
Q

At a low concentration, NO function as a ______ and as a hormone causing ______

A

Neurotransmitter

Vasodilation

29
Q

At high concentration, NO combines with _____ or with _____ to form RNOS

A

O2 superoxide

30
Q

RNOS is involved in neurodegenerative disease such as _______ and in chronic inflammation such as _____

A

Parkinson’s disease

Rheumatoid arthritis

31
Q

NO is synthesized by the enzyme _______ from argnine

A

NO synthase

32
Q

NOS has 3 tissue specific Isoform

A

Neuronal
Endothelial
Inducible

33
Q

Neuronal and endothelial NOS are tightly regulated by ____ concentration and generate NO that serve as _____ or ______

A

Calcium
Neurotransmitter
Hormone

34
Q

Inducible NOS are present in many cells of the immune system and can be induced to high level of expression and generate ______

A

RNOS

35
Q

NO exert direct toxicity by attack ______ of ETC and Fe-heme protein such as Hb and cytochromes

A

Fe-S center

36
Q

Under physiological condition, the effect caused by direct NO toxicity is low due to low abundance of ____

A

NO

37
Q

Direct NO toxicity can cause serious damage in individual with _____ or ischemia

A

Oxidative phosphorylation disease

38
Q

Superoxide dismutase converts _____ to _______

A

Superoxide

Hydrogen peroxide

39
Q

In response to infectious agents and other stimuli, phagocytic cells of the immune system exhibit a rapid consumption of O2, in a process called _______

A

Respiratory burst

40
Q

Respiratory burst is a major source of _______ (5 )

A 
Superoxide
Hydrogen peroxide
Hydroxyl radical
HOCl
RNOS
41
Q

Generation of free radical during _______ is intended to destroy invading microorganism or tumor cell.

A

Respiratory

42
Q

The respiratory burst results from the activity of _______, which catalyze the transfer of an electron from NADPH to O2 to form ______

A

NADPH oxidase

Superoxide

43
Q

Myeloperoxidase converts ______ to _______

A

H2O2

HOCl

44
Q

formation of hypochlorous acid from hydrogen peroxide is catalyzes by ________, a heme containing enzyme that is present only in phagocytic cell

A

Myeloperoxidase

45
Q

Peroxisomal fatty acyl-coa oxidase generates _______

A

hydrogen peroxide

46
Q

2 examples of endogenous free radical scavengers are _____

A

Uric acid

Melatonin

47
Q

Name 4 dietary free radical scavenger

A

Vitamin C
Vitamin E
Carotenoids
Flavonoids

48
Q

Vitamin E is ____ soluble and protect the membrane against _____

A

Lipid

Lipid peroxidation

49
Q

Reduced vitamin c can regenerated the ____ form of ____ by donating electron

A

Reduced

Vitamin E

Biochemistry 2 (11 decks)

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