Proteins are organic because they contain carbon atoms bonded to hydrogen atoms. This carbon-hydrogen bond is the defining characteristic of organic molecules. In addition to carbon and hydrogen, proteins are also composed of oxygen, nitrogen, and sometimes sulfur. These elements are arranged into building blocks called amino acids, which link together to form the complex structures of proteins.
The Building Blocks: Amino Acids
Amino acids are themselves organic molecules. As noted in various sources like this article on amino acids, organic chemicals are defined by the presence of carbon-hydrogen bonds. Each amino acid contains a carbon atom bonded to a hydrogen atom, along with other functional groups. The sequence and arrangement of these amino acids determine a protein's unique three-dimensional structure and function. This Scitable article on protein structure details how the amino acid sequence dictates the protein's shape.
The Role of Carbon
Carbon's ability to form four stable covalent bonds allows it to create long chains and complex structures, which are fundamental to the formation of proteins and other organic molecules. This is a key factor differentiating organic compounds from inorganic ones.
Key Characteristics Summarized:
- Presence of Carbon-Hydrogen Bonds: This is the fundamental criterion for classifying a molecule as organic.
- Amino Acid Composition: Proteins are polymers made up of chains of amino acids.
- Additional Elements: Proteins typically include oxygen, nitrogen, and sometimes sulfur in addition to carbon and hydrogen.
- Diverse Functions: Proteins have many vital roles in living organisms, including providing structure, catalyzing reactions, and transporting molecules. As stated in one source, proteins "provide cells with energy, form tissues, speed up chemical reactions throughout the body, and perform many other cellular functions." (Source)
