oxidative stress

what is oxidative stress

an imbalance between reactive oxygen species and a biological systems ability to detoxify them or repair the damage

what are reactive oxygen species

damaging chemical entities that are very reactive and damage other biological molecules

what are 3 main sources of ROS

mitochondrial electron transport, enzymatic reactions, immune cell activity and external factors

give examples of endogenous sources of ROS

mitochondria, NADPH oxidase and inflammatory cekks

Give examples of exogenous sources of ROS

Air pollution, radiation, UV exposure and cigarette smoke

what biological actions do ROS have on cells

ROS act as signalling molecules at low levels but can oxidise DNA, proteins and lipids at high levels leading to cellular dysfunction

what is an antioxidant

a compound that has the ability to prevent or repair the damage caused by oxidation

what is the difference between enzymatic and non enzymatic antioxidants

enzymatic antioxidants are proteins that catalytically remove ROS and non-enzymatic antioxidants are small molecules that directly scavenge ROS

give examples of enzymatic antioxidants

superoxide dismutase, catalase and glutathione peroxidase

give examples of non enzymatic antioxidants

glutathione and Vitamin E

how do antioxidants protect cells biologically

antioxidants reduce neutralise or convert ROS into less harmful molecules this protects DNA proteins and lipids from oxidative damage

what are the biological consequences of oxidative stress

oxidative stress causes DNA mutation lipid peroxidation protein damage inflammation cell death and contributes to ageing and diseases

how does oxidative stress contribute to disease development

it promotes chronic inflammation damages tissues and drives conditions like cancer cardiovascular disease neurodegeneration and diabetes

how do ROS damage DNA proteins and lipids

ROS oxidase bases in DNA break strands modify amino acids in proteins and initiate lipid peroxidation in membranes

how does the cell normally maintain redox balance

through antioxidant enzymes small molecule antioxidants repair systems and controlled ROS production