1 Explain why xrays can be used for steralization whereas ul

1) Explain why x-rays can be used for steralization, whereas ultraviolet rays can be used on for surface disinfection of materials.

2) Explain the mechanism of action of ultraviolet radiation on cells.

Solution

1. RADIONS USED FOR STERILIZATION ARE 2 TYPES-

a. IONIZING RADIATION (X RAYS)- it has short wavelenght and high energy so it easily penetrates cells and disrupts the DNA. so Xray is able to kill a microbe.

b. NON IONIZING RADIATION ( UV RAY)- IT HAS LONGER WAVELENGHT AND LOWER ENERGY, SO IT CANT PENETRATE THE CELL. IT IS THE REASON UV RAY IS USED FOR SURFACE STERILIZATION.

2.UV ray action on the cell- it does not posses sufficient energy for penetration but it act as a potent mutagen in prokaryotes. at 254nm DNA absorbs maximum UV ray. it is mainly absorbed by the pyrimidine thymine and cytocine in DNA ; and lead to the formation of pyrimidine dimer and hydrates.

thymine dimer are most common form of UV ray damage this disrupts the double helical structure and also interfare with DNA replication.