1. Oxidative Stress and Damage:
* Lipid peroxidation: Free radicals can attack and damage lipids (fats) in cell membranes, disrupting their integrity and causing cell dysfunction.
* Protein oxidation: They can modify proteins, altering their structure and function, leading to enzyme inactivation or misfolding.
* DNA damage: Free radicals can damage DNA, leading to mutations and increased risk of cancer.
* Cell signaling disruption: They can interfere with normal cell signaling pathways, leading to abnormal cell growth and function.
2. Disease Contribution:
* Aging: Oxidative stress is a major contributor to aging, as it accumulates over time and damages cells and tissues.
* Cancer: Chronic oxidative stress can damage DNA and contribute to the development of cancer.
* Cardiovascular disease: Free radicals contribute to the formation of atherosclerotic plaques in blood vessels, increasing the risk of heart attacks and strokes.
* Neurodegenerative diseases: They contribute to neuronal damage and cell death, implicated in diseases like Alzheimer's and Parkinson's.
* Inflammation: ROS play a role in inflammation, which can contribute to chronic diseases.
3. Defense Mechanisms:
Cells have evolved various defense mechanisms to neutralize free radicals and protect themselves from oxidative stress:
* Antioxidant enzymes: Superoxide dismutase (SOD), catalase, and glutathione peroxidase are enzymes that break down and detoxify free radicals.
* Antioxidant molecules: Vitamins C and E, glutathione, and carotenoids are powerful antioxidants that can neutralize free radicals.
* Repair mechanisms: Cells have repair mechanisms to fix damaged DNA, proteins, and lipids.
In summary:
Free oxygen radicals are highly reactive and damaging to cells. Cells must neutralize them to prevent oxidative stress, protect themselves from disease, and maintain their integrity and function. This is achieved through various defense mechanisms, including antioxidant enzymes, molecules, and repair pathways.
