Oxford tutorial question: you are an amino acid in the lumen of the small intestine. You are looking at transporter proteins protruding from the apical surfaces of intestinal epithelial cells. Your ambition is to be part of one of those membrane transporters. You will be asked to describe your adventures during one of three phases of your journey: beginning from the challenge of entering the epithelial cell, until you have been loaded onto an appropriate trna. The small intestine is the site where most of the nutrients from ingested food are absorbed and this is where proteins are decomposed to single amino acids by digestion. Amino acids are the building blocks of proteins, which give this amino acid hope in its quest to becoming a membrane transport protein. So, the goal of the amino acid is to get from the lumen of the intestines to the internal environment of the epithelial cells.