Ultraviolet light damage caused

Photocycloaddition and photoaddition provide good models for the mechanism by which ultraviolet light can cause damage to nucleic acids. When ultraviolet light damages DNA, the principal reactions occurring involve the nucleic acid bases. Photocycloaddition reactions to form... 

Bacteria such as Escherichia coli have four different mechanisms to repair ultraviolet light damage. However, even a repair process can make a mistake. Mutations occur when the UV damage repair system makes an error and causes a change in the nucleotide sequence of the DNA. 

The cyclobutane derivatives can revert to the original bases when irradiated with shorter-wavelength light. This reaction is involved in the repair process, which helps keep damage caused by ultraviolet to a minimum. Some repair mechanisms involve enzymes that are important in the breakdown of cyclobutane dimers by longer-wavelength light. 

Why does ultraviolet light cause more damage to our skin than visible light ... 

S.O.S. REPAIR A repair process that is error-prone, in that it generates mutations best characterized in the bacterium E. coli, S.O.S. repair depends on recA+ and lexA+ gene functions and is inducible by DNA damage caused by ultraviolet light and some chemical mutagens. 

Recent progress in the details of the metabolism of HA has also clarified the long appreciated observations that chronic inflammation, and sun damage caused by ultraviolet light cause premature aging of skin. These processes as well as normal aging, all utilize similar mechanisms that cause loss of moisture and changes in HA distribution. 

D. The damage to DNA caused by ultraviolet light (pyrimidine dimers) can be repaired by the excision repair pathway. In some cases, the missing enzyme is a repair endonuclease. 

Excessive exposure to environmental pollution (e.g. exhaust fumes), ultraviolet light or cigarette smoke and illness can cause the body to produce harmful radicals. It has been estimated, for example, that 1014 radicals, which include NO and N02 are present in one puff of cigarette smoke. Left unchecked, destructive radicals can lead to a number of diseases in humans, including arthritis, cancer and Parkinsonism. Radicals may also start the damage that causes fatty deposits in the arteries, leading eventually to heart disease or a stroke, and experimental work points to the role of radicals in bovine spongiform encephalopathy(BSE). 

---