What do organic compounds contain that inorganic compounds do not?

Organic compounds are primarily characterized by the presence of carbon and hydrogen atoms, which form what are known as hydrocarbon groups. These groups are fundamental to the structure and function of organic molecules, such as carbohydrates, lipids, proteins, and nucleic acids. The unique properties of carbon, including its ability to form stable bonds with other atoms and to create complex and varied structures, are central to organic chemistry.

In contrast, inorganic compounds typically do not contain carbon-hydrogen (C-H) bonds. While they may include carbon atoms, such as in carbonates or carbides, they lack the hydrocarbons that define organic compounds. This distinction is essential in various biological processes, as it defines how substances interact within a living organism.

The other options refer to various components that can be found in both organic and inorganic compounds. For example, protein structures, while prevalent in organic compounds, do not represent a defining feature of all organic substances. Likewise, minerals and water molecules play significant roles in both organic and inorganic chemistry, making them unsuitable for defining organic compounds specifically.