EESA10H3 Chapter Notes - Chapter 8: P53, Squamous Cell Carcinoma, Bromomethane
10 Apr 2013
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Document Summary
Uv radiation responsible for photochemical smog, bleaching of paints and decay of plastics. Conjugated bonds in organic molecules absorb uv radiation which damages these molecules. Oxygen produced by photosynthesis forms a filter in the outer reaches of the atmosphere that absorbs the most energetic and harmful uv radiation. The oxygen splits up and forms ozone; ozone layer can absorb uv radiation of higher wavelengths. Less energetic radiation is not absorbed by the ozone layer and reaches ground level. The uv radiation in uvb band still reaches ground level and can have deleterious effects on cells. Uva radiation is less photochemically active and less harmful than uvb light. We have adapted to uv stress by forming protective uv absorbing surface layers, repairing cell damage or replacing damaged cells. Eyes less adapted but shielded by brows and squinting. Downward trend in the amount of stratospheric ozone has been measured in temperate and polar climate zones.
