Cellular life on Earth consists of protein and nucleic acid biopolymers encapsulated by a semi-permeable membrane. Any reasonable theory for the origin of cells must explain the formation of the two types of macromolecule, as well as their co-localization within a membrane bounded space. Here I describe a membrane-centric theory for the origin of cellular life, where prebiotic fatty acid molecules self-assemble into a bilayer membrane, this membrane binds amino acids, and eventually helps catalyze their polymerization into peptides. I will explain how extant life informs us of possible prebiotically relevant peptide precursors, and how membranes could promote and isolate polymerization reactions.