cellular energy

Our ancestor’s ‘leaky’ membrane answers big questions in biology

All life on Earth came from one common ancestor – a single-celled organism – but what it looked like, how it lived and how it evolved into today’s modern cells is a four billion year old mystery being solved by researchers at UCL using mathematical modelling.

Findings published today in PLOS Biology suggest for the first time that life’s Last Universal Common Ancestor (LUCA) had a 'leaky’ membrane, which helps scientists answer two of biology’s biggest questions:

1. Why all cells use the same complex mechanism to harvest energy

2. Why two types of single-celled organism that form the deepest branch on the tree of life – bacteria and archaea – have completely different cell membranes

The leakiness of the membrane allowed LUCA to be powered by energy in its surroundings, most likely vents deep on the ocean floor, whilst holding in all the other components necessary for life.

The team modeled how the membrane changed, enabling LUCA’s descendants to move to new, more challenging environments and evolve into two distinct types of single-celled organism, bacteria and archaea, creating the deepest branch of the tree of life.

Caption: Pumping and phospholipid membranes arose independently in archaea and bacteria. Credit: Victor Sojo et al.