Which statement best describes alkylating agents?

Which statement best describes alkylating agents?

• A. Bind to RNA and inhibit transcription
• B. Damages DNA by causing breaks in double-stranded helix
• C. Stabilize microtubules to block mitosis
• D. Mimic purine and pyrimidine

Answer: (B)

Alkylating agents work by covalently attaching alkyl groups to DNA bases, most often on guanine, which creates cross-links between DNA strands or within a strand. These cross-links block DNA replication and transcription, and when cells try to copy the damaged DNA, double-strand breaks can occur, leading to cell death. That direct effect—causing damage that can result in breaks in the double helix during replication—is why this description best fits how alkylating agents act. They don’t primarily bind RNA to inhibit transcription, they don’t stabilize microtubules to stop mitosis, and they don’t mimic purines or pyrimidines.

Alkylating agents work by covalently attaching alkyl groups to DNA bases, most often on guanine, which creates cross-links between DNA strands or within a strand. These cross-links block DNA replication and transcription, and when cells try to copy the damaged DNA, double-strand breaks can occur, leading to cell death. That direct effect—causing damage that can result in breaks in the double helix during replication—is why this description best fits how alkylating agents act. They don’t primarily bind RNA to inhibit transcription, they don’t stabilize microtubules to stop mitosis, and they don’t mimic purines or pyrimidines.