Why must ultraviolet germicidal light operate within a specific wavelength range?

Why must ultraviolet germicidal light operate within a specific wavelength range?

• A. To disrupt feeding behavior
• B. To stimulate growth
• C. To cause mutations
• D. To limit replication

Answer: (D)

UV germicidal light is effective because it damages the genetic material of microorganisms, so they can’t replicate. In the UV-C range (roughly 200–280 nm, with a peak around 254 nm), nucleic acids absorb energy strongly and form lesions like pyrimidine dimers (such as thymine dimers) that block replication and transcription. If replication can’t proceed, the microbes cannot reproduce and are inactivated. Wavelengths outside this range don’t induce these lesions as efficiently, making disinfection far less effective. So the goal of using a specific UV-C range is to limit replication by damaging DNA or RNA.

UV germicidal light is effective because it damages the genetic material of microorganisms, so they can’t replicate. In the UV-C range (roughly 200–280 nm, with a peak around 254 nm), nucleic acids absorb energy strongly and form lesions like pyrimidine dimers (such as thymine dimers) that block replication and transcription. If replication can’t proceed, the microbes cannot reproduce and are inactivated. Wavelengths outside this range don’t induce these lesions as efficiently, making disinfection far less effective. So the goal of using a specific UV-C range is to limit replication by damaging DNA or RNA.