The first self-organizing membranous bundles of chemicals, arising spontaneously from inanimate materials and surrounded by lipids made the early Earth protocells. But these protocells almost certainly had to replicate without relying on large proteins. How they might have replicated is a key question for astrobiologists and biochemists studying the origins of life.

     A mathematical model by R. Attal (Biophysical Journal) proposes that heat alone may have promoted fission of one protocell into two.  Metabolic-like chemical reactions within a lipid membrane could isolate protocell metabolism from the randomness in the rest of Earth’s primordial chemical world and this partitioning, provided by the lipid membrane, might create an area of lower entropy.
    Mitochondria, which are capable of fissionable division, have a slightly higher internal temperature than the cytoplasm.

     Attal's theoretical thermodynamic model suggests that the heat generated could cause lipid bilayers regions to flip expanding the surrounding membrane and possibly result in the protocell pinching into two.

     While the model may not be the most accurate, it is a starting point for further experiments. Chemical reactions do generate heat, which could have an effect on things like protocell fission.