Which of the following is the simplest amino acid?

Glycine is recognized as the simplest amino acid due to its structure, which contains only a single hydrogen atom as its side chain (R group). This unique feature makes glycine the smallest amino acid, allowing it to play a crucial role in various biological processes, such as the synthesis of proteins and neurotransmitters.

The simplicity of glycine’s structure facilitates its participation in the formation of peptide bonds, which are essential for building proteins. It also contributes flexibility to protein structures, enabling the formation of tighter turns and loops.

In contrast, the other amino acids possess more complex structures with additional side chains that contribute to their unique properties. Alanine has a methyl group as its side chain, serine has a hydroxymethyl group, and arginine contains a guanidinium group, making them larger and more complex compared to glycine. Thus, glycine's minimalistic structure underscores its classification as the simplest amino acid.