Proteins are organic molecules primarily composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). Sulfur (S) is also a common component in many proteins.
Building Blocks: Amino Acids
The fundamental building blocks of proteins are amino acids. These small organic molecules each contain a central carbon atom bonded to:
- An amino group (-NH₂)
- A carboxyl group (-COOH)
- A hydrogen atom (-H)
- A unique side chain (R-group) – This side chain varies among the 20 different amino acids, determining each amino acid's properties and the overall protein structure.
The sequence and arrangement of these amino acids determine the protein's unique three-dimensional structure and function. This structure dictates a protein's role in numerous biological processes.
References Supporting Chemical Composition:
The provided text explicitly states that a protein molecule is made of the elements carbon, hydrogen, nitrogen, oxygen, and sulfur. (Reference 1). Numerous other references confirm this basic composition, emphasizing the role of amino acids as the building blocks and the presence of these key elements (Reference 2, Reference 8, Reference 10). While some references focus on specific types of proteins and their additional components, or on the overall chemical analysis of different protein sources (Reference 3, Reference 4, Reference 5, Reference 6, Reference 7, Reference 9), they all support the core chemical composition described above.
[Reference 1]: A protein molecule is an organic molecule made of the elements carbon, hydrogen, nitrogen, oxygen, and sulfur. The building blocks of protein contain a central carbon linked to a side chain group, an amine group, a carbonyl group and a hydrogen atom.
[Reference 2]: https://www.nature.com/scitable/topicpage/protein-structure-14122136/
[Reference 3]: https://www.sciencedirect.com/science/article/pii/S0377840120304351
[Reference 4]: https://pubmed.ncbi.nlm.nih.gov/16160054/
[Reference 5]: https://www.sciencedirect.com/science/article/pii/0308814689900307
[Reference 6]: https://pubmed.ncbi.nlm.nih.gov/15453686/
[Reference 7]: https://socratic.org/questions/what-is-the-chemical-composition-of-proteins
[Reference 8]: https://jamanetwork.com/journals/jamaophthalmology/fullarticle/610967
[Reference 9]: https://fas.biomedcentral.com/articles/10.1186/s41240-016-0012-1
[Reference 10]: https://study.com/learn/lesson/protein-molecule-function-examples-molecular-structure.html
