Reactive Oxygen Species (ROS)

Question 1

A …… is a molecule that has a single unpaired electron in an orbital and is highly reactive that is scavenged by antioxidants

Answer 1

Free Radical

Question 2

………… include free radicals and compounds leading to free radicals.

Answer 2

Reactive Oxygen Species

Question 3

Superoxide, hydroxyl radical, nitric oxide, nitrogen dioxide are…..

Answer 3

Free Radicals

Question 4

Hydrogen peroxide and peroxynitrite

are….

Answer 4

Species leading to free radicals

Question 5

ROS and RNOS are formed during ……. and need to be scavenged in order to prevent ……… related to DNA, lipids and proteins.

Answer 5

Oxidative stress

cell damage

Question 6

ROS formation is increased by:

Answer 6

• High oxygen tension (Example COPD patients on supplement oxygen).
• Hypoxia, carbon monoxide poisoning, ischemic reperfusion.
• High levels of acetaldehyde in the liver after ethanol abuse.

Question 7

CoQ, a lipid component of the Electron Transport Chain (ETC), can accidentally transfer one electron to molecular oxygen. This generates……….

Answer 7

Superoxide

Question 8

Superoxide is scavenged by………which uses two superoxides at the same time as substrates. The product is …….

Answer 8

Superoxide dismutase (SOD) 
Hydrogen peroxide.

Question 9

……….. is lipid soluble and can diffuse through membranes which leads to hydroxyl radicals when it is not scavenged.

Answer 9

Hydrogen Peroxide

Question 10

Hydroxyl radical OH. is formed from hydrogen peroxide interaction with superoxide called the……… reaction

Answer 10

Haber-Weiss Reaction

Question 11

Hydroxyl radical OH. is formed from hydrogen peroxide interaction with ferrous iron called the……… reaction

Answer 11

Fenton Reaction

Question 12

……….is the most detrimental ROS.

Answer 12

Hydroxyl radical OH.

Question 13

Hydrogen peroxide is scavenged by:

Answer 13

Catalase or by Glutathione peroxidase

Question 14

………. is found mainly in peroxisomes and degrades hydrogen peroxide when the peroxisomal hydrogen peroxide level gets too high

Answer 14

Catalase

Question 15

…………. acts on hydrogen peroxidase needs selenium as cofactor and uses 2 molecules of reduced glutathione (GSH).

Answer 15

Glutathione peroxidase

Question 16

If the peroxidized fatty acids are not repaired by……….. then they will be shortened to smaller segments resulting in “leaking” of membranes.

Answer 16

Glutathione peroxidase

Question 17

…………. more susceptible to ROS damage than nuclear DNA as it does not have histones and it is close to the ETC

Answer 17

Mitochondrial DNA

Question 18

A crushing injury leads to the formations of …….. in the Fenton reaction due to loss of sequestration of iron.

Answer 18

Hydroxyl Radicals

Question 19

Enzymatic radical scavengers:

Answer 19

Superoxide dismutase (SOD)
Catalase
Glutathione peroxidase

Question 20

Nonenzymatic endogenous radical scavengers:

Answer 20

▪ Uric acid (High levels can lead to gout)
▪ Glutathione (Released by the liver into the blood)
▪ Bilirubin (High levels can lead to jaundice)

Question 21

Dietary radical scavengers:

Answer 21

vitamins C and E, carotenoids, flavonoids, phytochemicals, polyphenols, isoprenoids and PUFA

Question 22

…… is a deadly degenerate disease of upper and lower motor neurons that control voluntary muscle movement

Answer 22

Amyotrophic Lateral Sclerosis (ALS)

Question 23

ALS is caused by a deficiency of …….

Answer 23

Superoxide dismutase (SOD)

Question 24

Symptoms of ALS:

Answer 24

Symptoms: 

• Difficulty breathing, vocal cord dysfunction.
• Head drop due to weakness of the neck muscles. 
• Muscle weakness, twitching, atrophy, dysphagia, hyper-reflexia.

Question 25

Neutrophils uses NADPH oxidase to synthesize…..

Answer 25

Superoxide

Question 26

…… forms hypochlorous acid which destroys bacteria and fungi

Answer 26

Myeloperoxidase

Question 27

…………..formed in macrophages by ………… is needed for RNOS formation as cell defense

Answer 27

Nitric Oxide (NO)
Inducible NO synthase (iNOS)

Question 28

Functions of nitric oxide:

Answer 28

• Relaxes smooth muscle and leads to vasodilation. 
• Prevents platelet aggregations. 
• Functions as neurotransmitter in brain. 
• Destruction of invading bacteria.

Question 29

Disease: Hereditary (X-linked) NADPH oxidase deficiency that results in Recurrent severe infections by bacteria (pneumonia) or fungi (aspergillus)

Answer 29

Chronic Granulomatous Disease (CGD)

Question 30

Disease: Recurrent severe infections by candida albicans caused by decreased formation of HOCL (bleach). Resulting in Oral and Genital Infections and systemic Infections

Answer 30

Myeloperoxidase Deficiency