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Flashcards in Oxygen Toxicity Deck (50):
0

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

Oxygen radicals

1

______ is probably the most potent ROS

Hydroxy radical

2

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

4
Superoxide, hydrogen peroxide
Hydroxyl radical, water

3

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

ROS

4

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

hydroxyl radicals
hydrogen peroxide

5

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

transition metals
Injury

6

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

Nitric oxide (NO)

7

Free radical nitric oxide is produced endogenously by enzyme _______

Nitric oxide synthase (NOS)

8

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

Coenzyme Q (CoQ)

9

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

One-electron reduced
Superoxide

10

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

Oxidase
Peroxidase
Oxygenase

11

_______ enzymes are a major source of free radical leakage

Cytochrome P450

12

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

Alcohol
Drug
Chemical toxicant

13

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

Hydrogen peroxide
Lipid peroxide

14

Peroxisomal ________ generates hydrogen peroxide

Fatty acyl-CoA oxidase

15

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

Eicosanoids

16

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

Hydroxyl
Hydrogen radical

17

Ionizing radiation can generate organic radical through direct collision with ______

Organic cellular component

18

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

Chain reaction
ROS

19

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

Hydroxyl radical
Polyunsaturated fatty acid

20

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

O2
Lipid peroxyl radial
Lipid peroxide

21

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

Free radical production

22

_____ of lipid molecules can cause lipid degradation

Peroxidation

23

_____ formed from lipid peroxidation can _____ proteins

Aldehyde
Cross-link

24

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

Fragmentation
Crosslinking
Aggregation

25

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

Glutathione

26

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

Base alteration
Deoxyribose

27

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

Free radical

28

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

Neurotransmitter
Vasodilation

29

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

O2 superoxide

30

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

Parkinson's disease
Rheumatoid arthritis

31

NO is synthesized by the enzyme _______ from argnine

NO synthase

32

NOS has 3 tissue specific Isoform

Neuronal
Endothelial
Inducible

33

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

Calcium
Neurotransmitter
Hormone

34

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

RNOS

35

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

Fe-S center

36

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

NO

37

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

Oxidative phosphorylation disease

38

Superoxide dismutase converts _____ to _______

Superoxide
Hydrogen peroxide

39

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

Respiratory burst

40

Respiratory burst is a major source of _______ (5 )

Superoxide
Hydrogen peroxide
Hydroxyl radical
HOCl
RNOS

41

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

Respiratory

42

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

NADPH oxidase
Superoxide

43

Myeloperoxidase converts ______ to _______

H2O2
HOCl

44

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

Myeloperoxidase

45

Peroxisomal fatty acyl-coa oxidase generates _______

hydrogen peroxide

46

2 examples of endogenous free radical scavengers are _____

Uric acid
Melatonin

47

Name 4 dietary free radical scavenger

Vitamin C
Vitamin E
Carotenoids
Flavonoids

48

Vitamin E is ____ soluble and protect the membrane against _____

Lipid
Lipid peroxidation

49

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

Reduced
Vitamin E