The term PART OF DNA can be solved by the four-letter word ACID. DNA, or deoxyribonucleic ACID, is a molecule that contains genetic information and is found in all living organisms. It is composed of two strands that are held together by chemical bonds called hydrogen bonds. The strands are made up of four different types of molecules, known as nucleotides, which are adenine, cytosine, guanine, and thymine. These molecules are held together by the ACID, which is the part of the DNA that is being referred to in this crossword puzzle.