In glycine, the simplest amino acid, the R group is a hydrogen atom, but in all other amino acids it is contains one or more carbon atoms bonded to hydrogens, and may contain other elements such as sulfur, oxygen or nitrogen.
ɪn ɡlˈaɪsiːn, ðə sˈɪmpəlɪst ɐmˈiːnoʊ ˈæsɪd, ðɪ ˈɑːɹ ɡɹˈuːp ɪz ɐ hˈaɪdɹədʒən ˈæɾəm, bˌʌt ɪn ˈɔːl ˈʌðɚɹ ɐmˈiːnoʊ ˈæsɪdz ɪɾ ɪz kəntˈeɪnz wˈʌn ɔːɹ mˈoːɹ kˈɑːɹbən ˈæɾəmz bˈɑːndᵻd tə hˈaɪdɹədʒənz, ænd mˈeɪ kəntˈeɪn ˈʌðɚɹ ˈɛlɪmənts sˈʌtʃ ɐz sˈʌlfɜː, ˈɑːksɪdʒən ɔːɹ nˈaɪtɹədʒən.