Since tetrahydrofolate is needed to make both purines and pyrimidines, which are building blocks of DNA and RNA, dihydrofolate reductase is targeted by various drugs to prevent nucleic acid synthesis.
The necessity of tetrahydrofolate for purines and pyrimidines, which are essential components of DNA and RNA, leads to the targeting of dihydrofolate reductase by various drugs to prevent nucleic acid synthesis.