Referring to following articles, I would like to know on what problem is for not able to converting the energy of the UV photon into heat within human body, which would lead to the generation of free radicals or other harmful reactive chemical species.
Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions :>
Photoprotection in Humans
Photoprotection of the human skin is achieved by extremely efficient internal conversion of DNA, proteins and melanin. Internal conversion is a photochemical process that converts the energy of the UV photon into small, harmless amounts of heat. If the energy of the UV photon were not transformed into heat, then it would lead to the generation of free radicals or other harmful reactive chemical species (e.g. singlet oxygen, or hydroxyl radical).
In DNA this photoprotective mechanism evolved four billion years ago at the dawn of life.[7] The purpose of this extremely efficient photoprotective mechanism is to prevent direct DNA damage and indirect DNA damage. The ultrafast internal conversion of DNA reduces the excited state lifetime of DNA to only a few femtoseconds (10−15s)—this way the excited DNA does not have enough time to react with other molecules.
For melanin this mechanism has developed later in the course of evolution. Melanin is such an efficient photoprotective substance that it dissipates more than 99.9% of the absorbed UV radiation as heat. [8] This means that less than 0.1% of the excited melanin molecules will undergo harmful chemical reactions or produce free radicals.The process of Sunburn would lead to the generation of free radicals or other harmful reactive chemical species (e.g. singlet oxygen, or hydroxyl radical).
I would like to know on which process to generate free radicals, would it be Apoptosis?
Does anyone have any suggestions?
Thanks, to everyone very much for any suggestions :>
Due to the excellent photochemical properties of DNA, this nature-made molecule is damaged by only a tiny fraction of the absorbed photons. DNA transforms more than 99.9% of the photons into harmless heat[3] (but the damage from the remaining < 0.1% is still enough to cause sunburn).[1] The transformation of excitation energy into harmless heat occurs via a photochemical process called internal conversion. Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, commonly from the sun. Moderate sun tanning without burning can also prevent subsequent sunburn, as it increases the amount of melanin, a photoprotective pigment that is the skin's natural defense against overexposure. Importantly, both sunburn and the increase in melanin production are triggered by direct DNA damage. When the skin cells' DNA is overly damaged by UV radiation, type I cell-death is triggered and the skin is replaced.https://en.wikipedia.org/wiki/Sunburnhttps://en.wikipedia.org/wiki/Direct_DNA_damageApoptosis (from Ancient Greek ἀπόπτωσις "falling off") is a process of programmed cell death that occurs in multicellular organisms.[2] Biochemical events lead to characteristic cell changes (morphology) and death.https://en.wikipedia.org/wiki/Apoptosis
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