核酸

1. Origins, structure, and basic meaning

• Structure: 核酸 (かくさん) denotes DNA- and RNA-class substances that store and transmit genetic information. 核酸の構造 gives a property; 核酸を取り出す makes it an extraction target.
• Basic usage: A class examines molecular structure with a model; a laboratory extracts nucleic acid from a sample.

2. Common pitfalls and similar expressions

• Molecular structure studied and substance extracted from a sample
  • The head noun in the first phrase is 構造; in the second, nucleic acid itself is the object. The term is a biological macromolecule class, not acids generally.