A persistent error has been observed among students in introductory biology and genetics. In interviews and examinations, many students express the belief that amino acids are produced by genetic translation (protein synthesis). The evidence suggests that at least four underlying factors contribute to error occurrence: (1) strong word association between the terms “amino acids” and “proteins”, (2) confusion resulting from familiar and unfamiliar levels of generality and specificity, (3) conflict resulting from the dual roles of some proteins as participants in and products of translation, and (4) lack of knowledge about the actual origins of amino acids in cells. Implications for teaching are discussed.