Antioxidants Flashcards
What are two substances that damage DNA
Xenobiotics and free radicals
Why can cell damage be worse than dead cells
Damaged cells can continue to proliferate and can generate more damaged cells
What is one side effect of cell damage
May divide uncontrollably (abnormal growth/tumor)’may be due to loss of contact inhibition
What do xenobiotics and free radicals cause
DNA damage, cell membrane damage; tend to attack double bonds
What are free radicals
Unpaired electrons
What do antioxidants do with free radicals
Neutralize them (donate electron for pairing)
What are external sources of oxidative stress
Smoking, radiation, carcinogens, drugs, hyperoxia, ozone
What are internal (cellular) sources of oxidative stress
Inflammatory cells, fibroblasts, endothelial cells, respiratory chain, xanthine and NADPH oxidase (reactions that generate ATP)
What enzyme system is involved in step 1 of neutralizing unpaired electron
Superoxidedemutase, SOD
What enzyme system is involved in step 2 of neutralizing unpaired electron
Catalase, GPx
What is lipid peroxidation
Attacking free radicals; autocatalytic (no enzymes required)
What is a major antioxidant in the cell membrane
Vitamin E (and glucathione peroxidase)
What are antioxidants in cytoplasm
Ascorbic peroxidase, GPx, Catalase, SOD
