Oxidative Stress and Cellular Damage
Start with the big picture
Free radicals contain unpaired electrons and can react with cellular molecules. Reactive oxygen species arise from sources such as mitochondrial electron transport, enzyme activity, phagocytes, and ionizing radiation; reactive nitrogen species can also contribute to injury. Oxidative damage affects lipids, proteins, and DNA, disrupting membranes, impairing enzymes, and promoting genetic changes. Cells counter these effects with enzymatic defenses, including superoxide dismutase, catalase, and glutathione-related enzymes, alongside non-enzymatic antioxidants such as vitamins E and C. Metal-binding proteins also help limit hydroxyl radical formation. When these defenses are insufficient, oxidative stress can contribute to cellular dysfunction and disease.
What you'll learn
- Define free radicals, reactive oxygen species, and oxidative stress.
- Identify major cellular sources of ROS and RNS.
- Describe how oxidative stress damages lipids, proteins, and DNA.
- Compare enzymatic and non-enzymatic antioxidant defenses.
- Explain how antioxidant systems and metal-binding proteins limit cellular injury.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
