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 nm 2. UV B 280 nm nm 3. UV C 100 nm nm Most is screened out by the ozone