Chemotherapy Biotherapy Certification ONS Practice Testq

Which category includes the drugs that block enzymes necessary for DNA synthesis?

1. Alkylating agents

2. Antimetabolites

3. Antitumor antibiotics

4. Topoisomerase inhibitors

The correct answer is: Antimetabolites

Antimetabolites are a class of chemotherapy drugs that interfere with the metabolic processes of cells, particularly those involved in DNA synthesis. They mimic the building blocks of DNA and RNA, leading to the incorporation of faulty nucleotides into the DNA strand, which eventually inhibits proper DNA replication and repair. By targeting the enzymes required for DNA synthesis, antimetabolites disrupt the normal cell cycle, especially in rapidly dividing cancer cells. This mechanism is particularly effective in treating malignancies, as these drugs exploit the differences between cancer cells and normal cells in their usage of metabolic pathways. Because cancer cells typically have a high rate of proliferation, they are more susceptible to the effects of antimetabolites, making this category highly relevant in cancer treatment protocols. The other categories—alkylating agents, antitumor antibiotics, and topoisomerase inhibitors—work through different mechanisms. Alkylating agents directly damage DNA by adding alkyl groups to the DNA helix, leading to cross-linking and preventing replication. Antitumor antibiotics interfere with the transcription process and also directly damage DNA. Topoisomerase inhibitors affect the enzymes that manage DNA structure during replication and transcription, thereby preventing the unwinding of DNA. However, it is the antimetabolites