Final answer:
DNA contains the instructions for making proteins and has a structure known as a double helix. The correct answer is C) Proteins; double helix.
Step-by-step explanation:
DNA stands for Deoxyribonucleic acid and contains the instructions for making proteins. The structure of a DNA molecule is a double helix which is like a twisted ladder. The correct answer to this question is C) Proteins; double helix.
A DNA molecule is made up of two strands wound around each other, resembling a spiral stair ladder. These two strands run in antiparallel directions, one from a 5' to 3' direction and the other from a 3' to 5' direction. Moreover, each strand has a backbone of alternating deoxyribose (a sugar) and phosphate groups, which function like the rails of a stair ladder. The strands are connected at each nucleotide by hydrogen bonds between nitrogenous bases: adenine with thymine and guanine with cytosine, akin to the teeth of a closed zipper. This elegant structure is pivotal for the DNA's role in encoding the information necessary for the synthesis of proteins, which are chains of amino acids tailored to perform various functions within living organisms.