NASA's OSIRIS-REx mission found ingredients for DNA and RNA on the asteroid Bennu. The discovery shows asteroids could seed planets with the precursors for life. It's also more evidence that life ...

DNA is made of four main building blocks — nucleobases called adenine (A), thymine (T), cytosine (C) and guanine (G). DNA's sister molecule, RNA, also uses A, C and G, but swaps out thymine for ...