How do antimetabolites mainly affect cellular functions?

Antimetabolites primarily affect cellular functions by disrupting the synthesis of nucleic acids, which are essential for DNA and RNA growth. These agents mimic natural substrates that are necessary for DNA and RNA production, ultimately leading to the incorporation of these analogs into the nucleic acid structure instead of the proper nucleotides. This misincorporation can halt DNA replication and disrupt RNA synthesis, thereby impairing cell division and function.

By blocking the growth of DNA and RNA, antimetabolites effectively inhibit the proliferation of rapidly dividing cells, such as cancer cells. This targeted mechanism is a crucial aspect of many cancer therapies, exploiting the higher reliance of cancer cells on these processes compared to normal cells.