Catalonia PAU Biology Practice Questions - Catalonia PAU Biology Examination - CIC Generalitat De Catalunya (Biologia 2n Batxillerat 2026) Exam

The alpha-carboxyl group of one amino acid and the alpha-amino group of another amino acid. The variable R-group side chain of a hydrophobic amino acid and a phosphate group. The hydroxyl group of a serine residue and the methyl group of an alanine residue. The aldehyde group of a reduced sugar and the imidazole ring of a histidine residue.