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Biochemistry > Oxygen Toxicity and Free Radicals > Flashcards

Oxygen Toxicity and Free Radicals Flashcards

1
Q

Protection against ROS and RNOS includes enzymes. Name some enzymes.

A

Superoxide Dismutase (SOD)
Catalase
Glutathione Peroxidase
Glutathione Reductase

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2
Q

The addition of one electron in oxygen generates?

A

superoxide O2-

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3
Q

The addition of a second electron in O2- generates?

A

H2O2

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4
Q

The addition of a third electron in H2O2 generates water and?

A

Hydroxyl radical

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5
Q

Addition of electron in OH radical makes?

A

water molecule

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6
Q

___________ is the most potent ROS

A

Hydroxyl radical

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7
Q

Chain reactions initiated by ___________ lead to

the formation of lipid peroxides and organic radicals

A

Hydroxyl radicals

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8
Q

The range of action of ____________ is limited by its reduced solubility

A

Superoxide

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9
Q

Hydrogen peroxide is not a radical, but easily generates hydroxyl radicals through interactions
with ____________.

A

transition metals (like Fe++, Cu+)

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10
Q

Superoxide reacts with NO to make ___________

A

Peroxynitrite

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11
Q

____________ (Coenzyme Q/Coenzyme A) generates superoxide as a by-product of the electron transport chain

A

Coenzyme Q

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12
Q

Most _____________ bind oxygen and transfer single electrons to oxygen via a metal cofactor

A

oxidases (NADPH oxidase)

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13
Q

_______________ enzymes attempt to detoxify xenobiotics by solubilizing them through
oxidation reactions

A

Cytochrome P450

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14
Q

Induction of cytochrome P450 enzymes by __________ leads to an increased generation of free radicals, and cellular injury

A

Alcohol, Drug or toxin

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15
Q

Ionizing radiation has sufficient energy that the radiation can split water into __________ and
hydrogen radicals

A

hydroxyl

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16
Q

Amino acids proline, histidine, arginine, cysteine, and methionine are susceptible to ___________-mediated attack and oxidative damage.

A

hydroxyl

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17
Q

Age-related macular degeneration is a leading cause of blindness. What is the role of free radicals here?

A

Oxidative damage to the retinal pigment epithelium.

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18
Q

NO can exert direct toxic effects by combining with ____________________ that also
have single electrons.

A

iron containing compounds

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19
Q

_______________ enzyme produces nitric oxide (NO)

A

Nitric Oxide synthase

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20
Q

Examples of RNOS include

A 
NO
peroxynitrite
peroxynitrous acid
nitrogen dioxide (NO2)
Nitronium ion
21
Q

RNOS can lead to __________ damage and loss of its activity.

A

protein

22
Q

____________ are given for angina because it will decompose to form NO, a potent vasodilator. This will increase blood flow to the heart, and reduce the pain.

A

Nitroglycerin pills

23
Q

____________ is also used as a second messenger

A

Nitric oxide

24
Q

In response to infectious agents and other stimuli, phagocytic cells of the immune system exhibit a rapid consumption of oxygen termed the ____________.

A

Respiratory burst

25
Q

The _______________ generates ROS, hypochlorous acid (HOCl), and RNOS in order to destroy
the phagocytosed materials

A

respiratory burst

26
Q

______________ catalyzes the formation of superoxide from oxygen and NADPH

A

NADPH oxidase

27
Q

___________ generates hypochlorous acid (HOCl) from H2O2, which is a powerful oxidant and destroys the contents of the phagosome.

A

Myeloperoxidase

28
Q

Chronic granulomatosis disease can result from genetic defects in _______________

A

NADPH oxidase

29
Q

In chronic granulomatosis disease, the patient exhibits enhanced susceptibility to bacterial and fungal infections because superoxide production during the respiratory burst is ___________ (increased/decreased)

A

decreased

30
Q

In ______________ disease, there is a dysregulation of normal inflammatory responses.

A

chronic granulomatosis disease

31
Q

__________ produces hydrogen peroxide and oxygen from two molecules of superoxide.

A

Superoxide dismutase

32
Q

SOD is located in _____________

A

mitochondria

33
Q

In familial ALS, defect in ________ is there which leads to oxidative damage leading to muscle failure

A

SOD

34
Q

___________ converts two molecules of hydrogen peroxide into two molecules of water and molecular oxygen.

A

Catalase

35
Q

Catalase is present in _____________ (organelle)

A

peroxisome

36
Q

The enzyme glutathione peroxidase requires ___________ metal

A

selenium

37
Q

Nonenzymatic antioxidants examples

A

Vitamin C
Vitamin E
Carotenoids
Flavonoid

38
Q

______________ is produced by the electron transport chain

A

Superoxide

39
Q

____________ cannot diffuse far from the site of origin

A

SUperoxide

40
Q

______________ can diffuse into and through cell membranes.

A

H2O2

41
Q

Hydroxyl radicals are produced from H2O2 in the _________ reaction in the presence of Fe2+ or Cu+

A

Fenton

42
Q

____________ is produced in neutrophils during the respiratory burst to destroy invading organisms

A

Hypochlorus acid (HOCl)

43
Q

The Attacking species in HOCl is _______

A

OCl-

44
Q

____________ decays so fast that it is probably not a significant in vivo source of toxicity

A

Singlet oxygen

45
Q

____________ is oxygen with antiparallel spins

A

Singlet oxygen

46
Q

___________ is produced at high oxygen tensions from absorption of UV light

A

Singlet oxygen

47
Q

Peroxynitrite can generate ______________

A

Nitrogen dioxide

48
Q

Which of the following is not a radical?

a. OH*
b. LOO*
c. NO2
d. ONOO-
e. NO

A

ONOO-

Biochemistry (15 decks)

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