The primary molecular structure found in DNA is the double helix. This structure consists of two long strands of nucleotides twisted around each other. Each nucleotide contains a phosphate group, a sugar (deoxyribose), and a nitrogenous base (adenine, thymine, cytosine, or guanine). The sequence of these bases encodes genetic information, while the specific pairing of adenine with thymine and cytosine with guanine is crucial for maintaining the stability and integrity of DNA. This structure is fundamental to genetic inheritance.