Which component of HAT medium is a cell poison that blocks metabolism?

Question

Quizplus · Accepted Answer

Aminopterin is a folic acid antagonist that inhibits the activity of dihydrofolate reductase, an enzyme required for the synthesis of nucleotides. This results in a depletion of nucleotides, which blocks metabolism of the cell and ultimately leads to its death. Thymidine and hypoxanthine are both nucleotides that can be used by cells to synthesize DNA and RNA, respectively, and are not cell poisons.

Which Component of HAT Medium Is a Cell Poison That