Biochemistry - Free Radicals and Oxygen Toxicity

Highly reactive electrons that are being unpaired

What are free radicals, and how do they contribute to cellular damage in the human body?

Cardiovascular diseases, chronic inflammation

How do lifestyle factors (e.g. smoking, poor diet, sun exposure) increase free radical production, and what diseases can result from excessive oxidative stress?

Lifestyle modification, antioxidants, proper exercise

What are the body’s natural defense mechanisms against free radicals, and how can individuals reduce their risk of oxidative stress-related damage?

d. A molecule with an unpaired electron in its outermost shell

Which of the following best describes a free radical?

a. A stable molecule with paired electrons in all its shells

b. A molecule that donates electrons to stabilize other molecules

c. A molecule that exclusively exists in the presence of oxygen

d. A molecule with an unpaired electron in its outermost shell

c. By promoting the development of atherosclerosis

How does oxidative stress contribute to the development of cardiovascular diseases?

a. By increasing the levels of antioxidants in the blood

b. By enhancing the repair of damaged blood vessels

c. By promoting the development of atherosclerosis

d. By reducing the production of free radicals in the heart

b. Fresh fruits and vegetables

Mrs. Johnson, a 65-year-old woman, has been recently diagnosed with age-related macular degeneration (AMD), a condition that can lead to vision loss. Her ophthalmologist recommends incorporating antioxidant-rich foods into her diet. Which of the following foods would be most beneficial for Mrs. Johnson’s condition?

a. Processed meats and fast food

b. Fresh fruits and vegetables

c. Sugary snacks and desserts

d. Deep-fried foods and potato chips

b. Oxidative stress increases the production of pro-inflammatory cytokines

Sarah, a 50-year-old woman, has been experiencing chronic inflammation in her joints, particularly in her knees. Her symptoms worsen during periods of physical activity. Upon examination, her doctor suspects that oxidative stress may be contributing to her condition. Which of the following mechanisms best explains the relationship between oxidative stress and joint inflammation?

a. Oxidative stress leads to the depletion of antioxidant enzymes

b. Oxidative stress increases the production of pro-inflammatory cytokines

c. Oxidative stress promotes the synthesis of anti-inflammatory molecules

d. Oxidative stress inhibits the migration of immune cells to the inflamed joints

Hemoglobin

What is the primary gas transporting molecule in red blood cells?

Oxygen and carbon dioxide

What gases are transported by hemoglobin?

As bicarbonate ions

In what form is carbon dioxide mostly transported in the blood?

To deliver oxygen to tissues and remove CO2 waste

Why are gas transporting molecules essential in the human body?

Cellular respiration

What process generates carbon dioxide in the body?

False

T/F: Hemoglobin is only responsible for oxygen transport.

False

T/F: Carbon dioxide is transported exclusively dissolved in plasma.

True

T/F: Hemoglobin facilitates efficient oxygen pickup and delivery.

False

T/F: Red blood cells do not play a role in gas transport.

True

T/F: Bicarbonate is the major form of carbon dioxide transport.

Heme group with iron

What component of hemoglobin binds to oxygen?

Cooperative binding

What type of binding allows efficient oxygen loading and unloading?

Conformational change

What structural change occurs upon oxygen binding?

Sickle cell anemia

Name a disease caused by hemoglobin mutation.

2,3-BPG

What molecule competes with O₂ for binding to hemoglobin (not same site)?

False

T/F: Each hemoglobin has one subunit.

True

T/F: Conformational change helps CO₂ bind more efficiently.

False

T/F: Sickle cell anemia results from normal hemoglobin.

False

T/F: DPG binds to the same site as oxygen in hemoglobin.

True

T/F: Hemoglobin helps in transporting both oxygen and carbon dioxide.

Bohr Effect

What effect describes CO₂ and pH's influence on O₂ binding?

Haldane Effect

What effect describes how O₂ affects CO₂ binding to hemoglobin?

Low oxygen concentration / High CO2

What factor causes hemoglobin to release oxygen in tissues?

Voxelotor

Name a therapeutic allosteric modulator of hemoglobin.

It decreases

What happens to hemoglobin’s CO₂ binding when O₂ increases?

True

T/F: The Bohr effect improves oxygen unloading in tissues.

False

T/F: Haldane effect describes the role of CO₂ in the lungs.

True

T/F: Allosteric modulation is essential in oxygen delivery regulation.

False

T/F: Voxelotor decreases oxygen affinity of hemoglobin.

False

T/F: Oxygen and DPG compete at the same site in hemoglobin.

Imbalance between free radicals and antioxidants

What causes oxidative stress?

DNA, lipids, or proteins

Name a cellular target damaged by oxidative stress.

It accumulates damage over time in cells and tissues

How does oxidative stress contribute to aging?

Alzheimer’s disease

Which disease is linked to oxidative stress in neurons?

False

T/F: ROS are completely harmless in the body.

False

T/F: Oxidative stress results only from external sources.

True

T/F: Chronic inflammation can be triggered by oxidative stress.

False

T/F: Aging has no relation to oxidative stress.

True

T/F: ROS damage includes lipid peroxidation.

Free radical

Unstable molecule with an unpaired electron

Oxidation during metabolism

What natural process forms free radicals?

Immune response (Inflammation)

Give one internal source of free radicals.

UV radiation (Tobacco smoke)

What external factor can generate free radicals?

Atherosclerosis (oxidized lipids)

How can free radicals lead to heart disease?

False

T/F: All free radicals are harmful to the body.

True

T/F: Free radicals can damage DNA and proteins.

False

T/F: Free radicals are only generated from environmental sources.

False

T/F: Free radicals are stable molecules.

True

T/F: They can contribute to diseases like cancer and stroke.

ROS: superoxide, hydrogen peroxide, hydroxyl radicals

What molecules cause oxygen toxicity?

Inflammatory pathways

What is a key pathway activated in oxygen toxicity?

Cell dysfunction or death

Name a result of unchecked ROS production.

ARDS (Acute Respiratory Distress Syndrome)

In what clinical condition is oxygen toxicity significant?

False

T/F: ROS are not involved in oxygen toxicity.

False

T/F: ROS formation is always harmful and should be avoided.

True

T/F: Inflammation is a key mechanism in oxygen toxicity.

False

T/F: Superoxide and hydroxyl radicals are harmless byproducts.

True

T/F: Oxygen toxicity can result from excessive oxygen therapy.

Antioxidants

Neutralize free radicals and prevent damage

Superoxide dismutase

Give an example of an enzymatic antioxidant.

Fruits and vegetables

Give a dietary source of non-enzymatic antioxidants.

By donating electrons

How do antioxidants stabilize free radicals?

Vitamin C (Vitamin E)

Name a non-enzymatic antioxidant vitamin.

False

T/F: Antioxidants only come from the diet.

True

T/F: Enzymatic antioxidants include catalase and glutathione peroxidase.

False

T/F: Antioxidants worsen oxidative stress.

True

T/F: Maintaining antioxidant balance is vital for homeostasis.

False

T/F: All antioxidants function by inhibiting enzymes.

Fatigue

What symptom is commonly associated with anemia?

Parkinson’s disease

Name one disease linked to increased oxidative stress.

COPD

Which respiratory condition is aggravated by free radicals?

Wrinkles (skin aging)

What is a visible sign of premature aging caused by oxidative stress?

Reduce damage and improve patient outcomes

How do antioxidant strategies help in clinical settings?

False

T/F: Oxidative stress is irrelevant in respiratory diseases.

True

T/F: Antioxidant therapy may be useful in managing oxidative conditions.

False

T/F: Chronic inflammation is not linked to oxidative stress.

True

T/F: Poor lifestyle choices can exacerbate oxidative stress.

False

T/F: Free radicals cannot be involved in cancer development.

True

T/F: Welding exposes individuals to UV and metal fumes that produce ROS.

False

T/F: Oxidative stress has no role in premature aging.

True

T/F: Free radicals can contribute to DNA damage.

True

T/F: Healthy diet and exercise reduce oxidative stress.

False

T/F: Case studies show no link between lifestyle and oxidative damage.