Oxygen Toxicity and Free Radicals

Question 1

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

Answer 1

Superoxide Dismutase (SOD)
Catalase
Glutathione Peroxidase
Glutathione Reductase

Question 2

The addition of one electron in oxygen generates?

Answer 2

superoxide O2-

Question 3

The addition of a second electron in O2- generates?

Answer 3

H2O2

Question 4

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

Answer 4

Hydroxyl radical

Question 5

Addition of electron in OH radical makes?

Answer 5

water molecule

Question 6

___________ is the most potent ROS

Answer 6

Hydroxyl radical

Question 7

Chain reactions initiated by ___________ lead to

the formation of lipid peroxides and organic radicals

Answer 7

Hydroxyl radicals

Question 8

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

Answer 8

Superoxide

Question 9

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

Answer 9

transition metals (like Fe++, Cu+)

Question 10

Superoxide reacts with NO to make ___________

Answer 10

Peroxynitrite

Question 11

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

Answer 11

Coenzyme Q

Question 12

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

Answer 12

oxidases (NADPH oxidase)

Question 13

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

Answer 13

Cytochrome P450

Question 14

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

Answer 14

Alcohol, Drug or toxin

Question 15

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

Answer 15

hydroxyl

Question 16

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

Answer 16

hydroxyl

Question 17

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

Answer 17

Oxidative damage to the retinal pigment epithelium.

Question 18

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

Answer 18

iron containing compounds

Question 19

_______________ enzyme produces nitric oxide (NO)

Answer 19

Nitric Oxide synthase

Question 20

Examples of RNOS include

Answer 20

NO
peroxynitrite
peroxynitrous acid
nitrogen dioxide (NO2)
Nitronium ion

Question 21

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

Answer 21

protein

Question 22

____________ 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.

Answer 22

Nitroglycerin pills

Question 23

____________ is also used as a second messenger

Answer 23

Nitric oxide

Question 24

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

Answer 24

Respiratory burst

Question 25

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

Answer 25

respiratory burst

Question 26

______________ catalyzes the formation of superoxide from oxygen and NADPH

Answer 26

NADPH oxidase

Question 27

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

Answer 27

Myeloperoxidase

Question 28

Chronic granulomatosis disease can result from genetic defects in _______________

Answer 28

NADPH oxidase

Question 29

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

Answer 29

decreased

Question 30

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

Answer 30

chronic granulomatosis disease

Question 31

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

Answer 31

Superoxide dismutase

Question 32

SOD is located in _____________

Answer 32

mitochondria

Question 33

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

Answer 33

SOD

Question 34

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

Answer 34

Catalase

Question 35

Catalase is present in _____________ (organelle)

Answer 35

peroxisome

Question 36

The enzyme glutathione peroxidase requires ___________ metal

Answer 36

selenium

Question 37

Nonenzymatic antioxidants examples

Answer 37

Vitamin C Vitamin E Carotenoids Flavonoid

Question 38

______________ is produced by the electron transport chain

Answer 38

Superoxide

Question 39

____________ cannot diffuse far from the site of origin

Answer 39

SUperoxide

Question 40

______________ can diffuse into and through cell membranes.

Answer 40

H2O2

Question 41

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

Answer 41

Fenton

Question 42

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

Answer 42

Hypochlorus acid (HOCl)

Question 43

The Attacking species in HOCl is _______

Answer 43

OCl-

Question 44

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

Answer 44

Singlet oxygen

Question 45

____________ is oxygen with antiparallel spins

Answer 45

Singlet oxygen

Question 46

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

Answer 46

Singlet oxygen

Question 47

Peroxynitrite can generate ______________

Answer 47

Nitrogen dioxide

Question 48

Which of the following is not a radical? a. OH* b. LOO* c. NO2 d. ONOO- e. NO

Answer 48

ONOO-