Hormones act as intercellular messengers, and they vary in chemical nature. Examples include steroids (estrogens, androgens), polypeptides (insulin, endorphins), and amino acid derivatives (epinephrine, norepinephrine). Hormones help maintain biological balance, as seen in insulin and glucagon regulating blood glucose levels.

While proteins are synthesized by various RNA molecules, the instructions for protein synthesis are encoded in DNA. DNA provides the genetic information used by RNA in the cell’s protein synthesis process.

DNA serves as the chemical basis of heredity, maintaining species identity over time. It undergoes self-duplication during cell division, transferring identical DNA strands to daughter cells.

Adenine pairs with thymine, and cytosine pairs with guanine through hydrogen bonds in DNA. RNA has a single-stranded helical structure, with messenger RNA (m-RNA), ribosomal RNA (r-RNA), and transfer RNA (t-RNA) serving different functions.

The primary structure of nucleic acids refers to the sequence of nucleotides in the chain, while the secondary structure, proposed by Watson and Crick, reveals a double-strand helix structure for DNA with complementary base pairs held by hydrogen bonds.