What kind of damage UV light is causing in DNA? What effect this damage has on...

What kind of damage UV light is causing in DNA? What effect this damage has on the cell growth?

Expert Solution

UVB light (315-280 nm) interferes directly with the bonding in DNA molecule between the nucleotides, leading to the formation of photochemical products. (eg-CPD, 6,4 PP)

Eg- cyclo butane pyrimidine dimer (CPDs) formed when two adjacent pyrimidines (thymines or cytosines) become linked covalently creating an intermediate, thymine dimmers, that is not normally found in DNA. They form causes a structural kink in the DNA that prevents the DNA replication (as it interfere with basepairing of pyrimidine). The mutation induced by UVB is C to T transversion.

Eg. 6-4 Photo Products are formed due to covalent bond between adjacent pyramidines (the 5’ end of C6 and 3’ end of C4). This lead to the formation of an unstable intermediate , thus form a kink in DNA , interfere with normal base pairing thereby replication.

On exposure to UV A radiation free radicals are produced in cells that oxidise DNA bases . The modified bases fail to correctly pair during replication and creates mutation.

Effect on cell growth

Damages in DNA sequences lead to formation of skin cancer. Melanoma is the most serious type of skin cancer that develop in melanocytes.

Programmed cell death (apoptosis) induced by UV-C light

gladiator answered 2 years ago

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