 Methylotrophic yeast species, e.g. Hansegular polymorpha, Pitchia pastoris, can grow on methanol as sole source of carbon and energy. During exponential growth on glucose cells typically contain a single, small peroxisum that is redundant for growth. Cells of H. polymorpha typically contain one organelles, which are crucial to support growth on methyl. During the shift of cells from glucose to methanol containing media, 20% of genes were significantly upregulated. This article was authored by Kipers-Oscarpey, De Jong-Anne, Susanna Kim-Ae, and others.