The variable group, also called the R group or side chain, determines the identity and many of the properties of a specific amino acid.
ðə vˈɛɹɪəbəl ɡɹˈuːp, ˈɔːlsoʊ kˈɔːld ðɪ ˈɑːɹ ɡɹˈuːp ɔːɹ sˈaɪd tʃˈeɪn, dɪtˈɜːmɪnz ðɪ aɪdˈɛntᵻɾi ænd mˈɛnɪəv ðə pɹˈɑːpɚɾiz əvə spəsˈɪfɪk ɐmˈiːnoʊ ˈæsɪd.