Which organic molecules form the major structural materials of the body?

Proteins

Explanation:

They are found everywhere in the body from muscle, cell membranes, hair, enzymes, and etcetera and are responsible for the phenotype of organisms. Proteins are the ultimate expression of genes in the DNA of organisms. The DNA is transcribed by DNA polymerase into mRNA, then mRNA is translated into protein by ribosomes. This general rule is called the central dogma.