Which molecule stores genetic information and is composed of nucleotides?

• A. Carbohydrate
• B. RNA
• C. DNA
• D. Protein

Answer: (C)

Genetic information is stored in a molecule built from nucleotides, and DNA is the molecule that does this in nearly all organisms. DNA is a long polymer with a sugar-phosphate backbone and four bases (adenine, thymine, cytosine, and guanine) that pair A with T and C with G, forming a stable double helix. The sequence of these bases encodes the instructions for building and maintaining an organism, and the double-stranded structure allows accurate copying during cell division. RNA is also made of nucleotides and plays a crucial role in expressing that genetic information, but its primary job is not long-term storage; it’s usually single-stranded and more transient. Carbohydrates and proteins do not store genetic information, so DNA best fits the description.