Chemotherapy Biotherapy Certification ONS Practice Testq

What class of drugs does not affect the cell cycle by interrupting DNA synthesis?

1. Antimetabolites

2. Alkylating agents

3. Topoisomerase inhibitors

4. Antitumor antibiotics

The correct answer is: Antimetabolites

The correct response identifies antimetabolites as a class of drugs that primarily disrupt DNA synthesis. However, this class actually interferes specifically during the S phase of the cell cycle by mimicking normal metabolites, thereby inhibiting the synthesis of nucleotides necessary for DNA replication. In contrast, alkylating agents function by adding alkyl groups to DNA, resulting in cross-links that prevent DNA replication and transcription. Topoisomerase inhibitors work by interfering with the enzymes that manage the topology of DNA, causing strand breaks and preventing proper DNA replication. Antitumor antibiotics also work by intercalating into DNA, disrupting replication and transcription processes. Ultimately, while antimetabolites do target the process of DNA synthesis, the characterization of which class disrupts the cell cycle without affecting DNA synthesis may require reevaluation. Alkylating agents, topoisomerase inhibitors, and antitumor antibiotics all impede forms of DNA replication through distinct mechanisms throughout various phases of the cell cycle.