How many different types of amino acids are there?

There are 20 different types of amino acids that are commonly found in proteins. These amino acids are the building blocks of proteins and play critical roles in various biological processes. Each amino acid has a distinct side chain, or R group, which determines its chemical properties and function.

The number 20 signifies the standard set of amino acids encoded by the universal genetic code used by most organisms. These amino acids can combine in numerous ways to form proteins, allowing for an immense diversity of protein structures and functions that are crucial to life.

While there are some variants and modified amino acids, such as selenocysteine and pyrrolysine, the core set used in protein synthesis remains 20. This established understanding is central to molecular biology and biochemistry, as it lays the foundation for how proteins are synthesized from genetic information.