1. What Is Nucleic Acid? Nucleic Acid Basics We've already talked about certain biochemical substances, like proteins, lipids, and saccharides, but there's one more important substance that we haven't covered yet--nucleic acids. As you might guess from the name, nucleic acids are acidic substances found in the nucleus of a cell. We looked at the nucleus of a cell earlier (see chapter 1), with a little help from robocat. We called it a "DNA warehouse." yeah! it's big, round, and seems really important. Perfect for our last lesson!