exists and is an alternate of . An R group is the chemical group attached to the alpha carbon in an amino acid. In proteins all amino acids have the same basic structure and vary only in their R group. There are 20 standard amino acids found in proteins, which all have different R groups. For example an amino acids with Hydrogen from its R group is glycine, and one carbon with 3 hydrogens (a methyl group) is the R group for alanine. An R group is the chemical group attached to the alpha carbon in an amino acid.