Why must a puritine pair with a pyradine?

Pairing of a specific purine to a specific pyrimidine is due to the structure and properties of each ring and the three-dimensional fit between complements. Purine and pyrimidine are organic, aromatic ring compounds that act as the building blocks of nucleic acid. In DNA, purines occur as adenine and guanine, while pyrimidines occur as thymine and cytosine. In DNA base pairing, adenine pairs with thymine, and guanine pairs with cytosine

False. records show otherwise

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.