When radiation energy is transferred directly to DNA, this is called:

When radiation energy is transferred directly to DNA, this is called:

• A. Indirect effect
• B. Mutations
• C. Direct effect
• D. Target theory

Answer: (C)

When radiation energy is transferred directly to DNA, you’re dealing with a direct effect. In this scenario, the radiation deposits energy right into the DNA molecule itself, causing ionizations and chemical changes that can break DNA strands or alter bases. This direct hit can lead to mutations or cell death if the damage isn’t repaired. In contrast, the indirect effect happens when radiation primarily interacts with surrounding water molecules, producing reactive radicals like hydroxyl radicals that then damage DNA. For many low-LET radiations (like x-rays and gamma rays), indirect damage is a major contributor, though direct damage still occurs. Target theory is about how damage relates to hitting critical molecular targets and the dose needed to inactivate a cell, not the mechanism by which energy is transferred to DNA. So the term that names energy transferred directly to DNA is the direct effect.

When radiation energy is transferred directly to DNA, you’re dealing with a direct effect. In this scenario, the radiation deposits energy right into the DNA molecule itself, causing ionizations and chemical changes that can break DNA strands or alter bases. This direct hit can lead to mutations or cell death if the damage isn’t repaired.

In contrast, the indirect effect happens when radiation primarily interacts with surrounding water molecules, producing reactive radicals like hydroxyl radicals that then damage DNA. For many low-LET radiations (like x-rays and gamma rays), indirect damage is a major contributor, though direct damage still occurs.

Target theory is about how damage relates to hitting critical molecular targets and the dose needed to inactivate a cell, not the mechanism by which energy is transferred to DNA. So the term that names energy transferred directly to DNA is the direct effect.