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Ultra-violet Radiation and Photoreactivation. Types of Radiation. 1. Ionizing Radiation X-rays and gamma rays Disrupts DNA and RNA Used for Sterilization Procedures 2. Non-Ionizing Radiation UV light Does not penetrate plastic, glass and proteinaceous matter (very well)
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Types of Radiation • 1. Ionizing Radiation • X-rays and gamma rays • Disrupts DNA and RNA • Used for Sterilization Procedures • 2. Non-Ionizing Radiation • UV light • Does not penetrate plastic, glass and proteinaceous matter (very well) • Not used for sterilization procedures, but is used to reduce microbial populations • lethal mutations – Thymine Dimers
Thymine Dimers • A T G C A T G T T C G A T G C A • T A C G T A C A A G C T A C G T
Photoreactivation • Enzymes activated by exposure to visible light can snip out the damaged DNA and replace it with the normal DNA
UV Radiation from the Sun • 1. UV A 320 nm - 400 nm • 2. UV B 280 nm - 320 nm • 3. UV C 100 nm - 280 nm • Most is screened out by the ozone