Proteins and the 20 proteinogenic amino acids

What’s an athlete’s favorite word? It’s probably protein, right? We all know proteins are fundamental to muscular development. They provide the necessary support, protection, transport, regulation, and movement to the human body.

Stressed for time? If you can only have the quickest read, you can go directly to Summary.

 The birth of a protein

Proteins are macromolecules which are formed through dehydration synthesis reactions leading to covalent bonds between monomers; a multitude of monomers forms polymers. Proteins are polymers of amino acids. Different compositions of amino acids form different types of proteins, with diverse structures and functions.

Proteins are also called polypeptides. Amino acids are covalently bonded by peptide linkages (e.g., a dipeptide is formed of two amino acids). As polypeptides, proteins are multiple-peptide chains of proteinogenic amino acids.

Proteinogenic amino acids are those organic compounds containing the amino (NH2) and the carboxyl (COOH) groups which are capable of producing proteins. There are twenty proteinogenic amino acids, eleven of which are non-essential (i.e., they can be synthesized by the human body and therefore are not imposed in our diets), leaving nine of them, the essential amino acids, as dietary requirements given they cannot be synthesized by the human body.

Protein sources – complete and incomplete proteins

Foods containing the nine essential amino acids are known as complete proteins. These include animal sources (meat, fish, milk, yogurt, whey, eggs), quinoa, buckwheat, hemp seeds, chia seeds, and spirulina.

On the other hand, plant foods are considered incomplete proteins that cannot provide all the essential amino acids. However, specific combinations will complement each other, so just adjust for complementary protein sources in your meal or throughout the day. The rule of thumb when it comes to complementary proteins is combining grains, cereals, nuts or seeds with beans, peas, lentils or peanuts (e.g., peanut butter on wheat bread).



Proteins are macromolecules as polymers of amino acids. Proteinogenic amino acids are those amino’s capable of producing proteins. There are twenty proteinogenic amino acids: eleven non-essential ones and nine essential ones (essential amino-acids are not synthesized by the human body and therefore need to be supplied through diet). These essential protein-builders are most easily obtained through animal products (meat, dairy, whey), quinoa, buckwheat, hemp seeds, chia seeds, and spirulina.

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  1. MITOpenCoursewear – Chemistry of Sports p. 11-16
  2. University of Massachusetts – Nibble Directory