In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: This element blocks the flow of calcium through NMDA channels, while compounds containing this metal are used to treat eclampsia. The hairpin ribozyme requires this metal to fold, and the the CorA protein transports this element across bacterial membranes. It is weakly bonded to the terminal phosphate groups of ATP. EDTA is used to chelate this metal, and it is found in a compound that contains a phytol side chain. Its stabilizing effect on the backbones of nucleic acids makes it a necessary cofactor for DNA polymerase, meaning its chloride is used in PCR reactions. Also found at the center of the porphyrin ring of chlorophyll, for 10 points, name this metal present as a +2 ion in solution, with atomic number 12 and symbol Mg.
A:
Science