Free Radical And Oxygen Toxicity Flashcards
Which label correctly identifies the primary site of superoxide generation in the mitochondrion?
[Insert diagram of mitochondrion with labeled complexes I-IV]
A. Complex I
B. Complex II
C. Complex III
D. Complex IV
Correct Answer: A
Identify the phase of lipid peroxidation shown in the diagram:
[Insert diagram showing initiation, propagation, and termination]
A. Initiation
B. Propagation
C. Termination
D. Recovery
Correct Answer: B
Which component in this antioxidant pathway is responsible for converting superoxide into hydrogen peroxide?
[Insert antioxidant enzyme pathway diagram]
A. Catalase
B. Glutathione peroxidase
C. Superoxide dismutase (SOD)
D. Peroxidase
Correct Answer: C
Which structure is the primary cellular source of ROS in the image below?
[Insert labeled cell diagram with nucleus, mitochondria, peroxisomes, lysosomes]
A. Lysosome
B. Peroxisome
C. Mitochondrion
D. Nucleus
Correct Answer: C
From the diagram, which step leads to the accumulation of lipid peroxides?
[Insert lipid peroxidation mechanism image with chain reactions]
A. Radical abstraction
B. Oxygen addition
C. Propagation
D. Accumulation
Correct Answer: D
Which of the following defines a free radical?
A. A molecule with all electrons paired
B. A molecule that donates protons
C. A species with one or more unpaired electrons
D. A molecule that loses oxygen
Correct Answer: C
What is the role of antioxidants in the body?
A. Generate free radicals
B. Pair with oxygen
C. Donate electrons to stabilize free radicals
D. Degrade proteins
Correct Answer: C
Which of the following is an example of a reactive oxygen species (ROS)?
A. CO2
B. O2*−
C. CH4
D. NH3
Correct Answer: B
Which organelle contributes most significantly to ROS production during aerobic respiration?
A. Lysosome
B. Endoplasmic reticulum
C. Golgi apparatus
D. Mitochondrion
Correct Answer: D
Which vitamin functions as a non-enzymatic antioxidant?
A. Vitamin K
B. Vitamin C
C. Vitamin B6
D. Vitamin D
Correct Answer: B
Assertion: Free radicals are involved in the aging process.
Reason: Free radicals cause cellular damage including DNA mutations and lipid peroxidation.
A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: A
Assertion: Antioxidants only function inside the cell.
Reason: Alpha-tocopherol is an antioxidant found only in intracellular spaces.
A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: D
Assertion: Hydrogen peroxide is a reactive oxygen species.
Reason: It is formed by the enzymatic activity of catalase.
A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: C
Assertion: Lipid peroxidation only occurs in prokaryotes.
Reason: Prokaryotes have mitochondria that generate ROS.
A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: D
Assertion: Mitochondria are a significant source of superoxide radicals.
Reason: Electrons may leak from the electron transport chain and react with oxygen.
A. Both A and R are true, and R explains A.
B. Both A and R are true, but R does not explain A.
C. A is true, R is false.
D. A is false, R is true.
Correct Answer: A
Free radicals have paired electrons.
False
Superoxide dismutase (SOD) converts superoxide to hydrogen peroxide.
True
Free radicals can be generated from external sources like radiation.
True
Catalase converts hydrogen peroxide into water and oxygen.
True
Lipid peroxidation stabilizes cellular membranes.
False
Hydroxyl radicals are the least reactive ROS.
False
Vitamin E is a non-enzymatic antioxidant found in the lipid phase.
True
Mitochondria are not involved in the production of ROS.
False
Exercise may increase ROS production in cells.
True
Glutathione peroxidase uses NADPH to reduce hydrogen peroxide.
False
Front
Back
Identify the free radical involved in site-specific oxidative DNA damage in the copper/H2O2 system.
[Insert diagram of copper-mediated Fenton reaction near DNA]
A. Superoxide
B. Singlet oxygen
C. Hydroxyl radical
D. Nitric oxide
Correct Answer: C
Which zone in the transplant organ diagram is most prone to ischemia-reperfusion ROS damage?
[Insert transplant tissue diagram with zones]
A. Outer cortex
B. Medullary core
C. Perivascular zone
D. Reperfusion edge
Correct Answer: D
From this antioxidant enzyme chart, which enzyme detoxifies lipid peroxides?
[Insert enzyme functions table]
A. Catalase
B. Glutathione reductase
C. Glutathione peroxidase
D. SOD
Correct Answer: C
Based on the mechanism diagram, what is the first reactive product when ROS attack polyunsaturated fatty acids?
[Insert lipid peroxidation chain reaction diagram]
A. Alcohol
B. Peroxyl radical
C. Ketone
D. Aldehyde
Correct Answer: B
In this pathway diagram of NF-κB activation, what triggers its translocation during oxidative stress?
[Insert pathway image with IκB degradation step]
A. Protein kinase inhibition
B. IκB degradation
C. Direct DNA binding
D. ROS depletion
Correct Answer: B
Which of the following enzymes directly contributes to ischemia-reperfusion injury in myocardial tissue?
A. Glutathione reductase
B. Superoxide dismutase
C. Xanthine oxidase
D. Nitric oxide synthase
Correct Answer: C
Which antioxidant system functions both intracellularly and extracellularly?
A. SOD
B. Alpha-tocopherol
C. Catalase
D. Glutathione
Correct Answer: B
Which reactive oxygen species is generated from NADPH oxidase in phagocytes?
A. Hydrogen peroxide
B. Hydroxyl radical
C. Superoxide
D. Nitric oxide
Correct Answer: C
Which dietary antioxidant is most effective at scavenging peroxyl radicals in lipid membranes?
A. Vitamin B1
B. Vitamin E
C. Vitamin C
D. Glutathione
Correct Answer: B
What is the role of ceruloplasmin in oxidative stress defense?
A. Transfers copper to DNA
B. Binds iron to prevent ROS generation
C. Scavenges hydrogen peroxide
D. Carries oxygen in blood
Correct Answer: B
Assertion: Antioxidant enzymes require trace elements for optimal function.
Reason: Selenium is needed for GPx and zinc/copper for SOD activity.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Vitamin E can reverse lipid peroxidation.
Reason: It interrupts propagation by donating hydrogen to lipid peroxyl radicals.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Free radicals promote carcinogenesis.
Reason: Oxidative DNA damage can activate oncogenes or inhibit tumor suppressor genes.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Catalase detoxifies singlet oxygen.
Reason: Catalase catalyzes conversion of hydrogen peroxide to water and oxygen.
C. A is true, R is false.
Correct Answer: C
Assertion: ROS generation can enhance HIV replication.
Reason: ROS activate NF-κB, which upregulates HIV transcription.
A. Both A and R are true, and R explains A.
Correct Answer: A
Alpha-tocopherol is water-soluble and acts in cytosol.
False
Allopurinol inhibits xanthine oxidase to reduce oxidative injury.
True
Ischemia alone causes more oxidative damage than reperfusion.
False
ROS can promote viral gene expression in infected lymphocytes.
True
Peroxyl radicals are detoxified by catalase.
False
8-oxoguanine is a mutagenic lesion in DNA caused by ROS.
True
SOD is an effective scavenger of hydroxyl radicals.
False
ROS contribute to endothelial injury in atherosclerosis.
True
Glutathione reductase uses NADPH to regenerate reduced GSH.
True
ROS play no role in neurodegenerative diseases.
False
Front
Back
Which label on the diagram corresponds to the site of ROS generation during ischemia-reperfusion?
[Insert diagram of tissue with ischemic and reperfusion zones labeled]
A. Ischemic zone
B. Reperfused zone
C. Necrotic core
D. Endothelial boundary
Correct Answer: B
Identify the enzyme responsible for hydrogen peroxide breakdown in the diagram of antioxidant defenses.
[Insert enzyme pathway showing SOD, catalase, GPx]
A. Superoxide dismutase
B. Glutathione reductase
C. Catalase
D. Lipase
Correct Answer: C
What step in the chain reaction is shown in this lipid peroxidation diagram?
[Insert diagram showing fatty acid radical reacting with O2]
A. Termination
B. Chain propagation
C. Antioxidant rescue
D. Initiation
Correct Answer: B
From the diagram of copper-mediated ROS generation, what is the product of H2O2 and Cu+?
[Insert ROS generation pathway]
A. O2−
B. OH
C. NO*
D. H2O
Correct Answer: B
What damage outcome is highlighted in this DNA damage diagram?
[Insert labeled DNA with 8-oxoguanine lesion and strand breaks]
A. Point mutation
B. Strand breakage
C. Protein oxidation
D. Membrane leakage
Correct Answer: B
Which reactive oxygen species is most associated with DNA strand breakage?
A. Superoxide
B. Hydrogen peroxide
C. Hydroxyl radical
D. Nitric oxide
Correct Answer: C
What is the role of glutathione peroxidase?
A. Converts lipid radicals to water
B. Removes hydrogen peroxide
C. Generates hydroxyl radicals
D. Breaks down fatty acids
Correct Answer: B
Which metal ion contributes to ROS generation in estrogen metabolism?
A. Zinc
B. Copper
C. Iron
D. Sodium
Correct Answer: B
Which organelle contributes to ROS through xanthine oxidase activity?
A. Nucleus
B. Golgi body
C. Peroxisome
D. Endoplasmic reticulum
Correct Answer: C
Which of the following enhances HIV gene expression through oxidative stress?
A. Lipid peroxides
B. Nuclear factor kappa B (NF-κB)
C. Glutathione dismutase
D. Beta-carotene
Correct Answer: B
Assertion: Copper catalyzes DNA damage through ROS generation.
Reason: Copper reacts with hydrogen peroxide to produce hydroxyl radicals.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Glutathione peroxidase requires selenium as a cofactor.
Reason: Selenium deficiency can impair antioxidant defense mechanisms.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Vitamin E acts in aqueous environments.
Reason: Vitamin E is lipid-soluble and protects membranes.
A. Both A and R are true, but R does not explain A.
Correct Answer: B
Assertion: ROS accelerate aging.
Reason: They induce DNA mutations, protein damage, and lipid peroxidation.
A. Both A and R are true, and R explains A.
Correct Answer: A
Assertion: Xanthine oxidase protects tissues from ROS.
Reason: It metabolizes hydrogen peroxide into water and oxygen.
C. A is true, R is false.
Correct Answer: C
Copper can promote ROS generation via Fenton-like reactions.
True
Hydrogen peroxide directly breaks DNA strands without any cofactors.
False
Glutathione is regenerated in the body using NADPH.
True
ROS are produced only during pathological conditions.
False
Selenium is a critical component of glutathione peroxidase.
True
Vitamin C is lipid-soluble and acts in membranes.
False
NF-κB activation is linked to oxidative stress in HIV infection.
True
DNA strand breaks from oxidative damage are irreversible.
False
Glutathione peroxidase converts lipid hydroperoxides into non-toxic alcohols.
True
Manganese is a required mineral for catalase activity.
False
