Submission + - Last universal ancestor (LUA) may have a 'leaky' membrane (ucl.ac.uk)
Taco Cowboy writes: Around four billion years ago the Last Universal Ancestor (LUA), most probably a single cell organism, appeared on Planet Earth. In order to be alive that single cell organism must be able to harness energy from its surrounding, and in order to do that, according to researchers at University College London (UCL), that single cell organism had a 'leaky' membrane which allowed protons to enter and exit at the same time
The UCL researchers came to the conclusion using mathematical modeling, in which the findings were published on August 13, 2014, in PLOS Biology
Illustrated picture at http://cdn.phys.org/newman/gfx...
The study claims this membrane may explain why all cells use the same complex mechanism to harvest energy, and it may also explain why two types of fundamental single-celled organisms — bacteria and archaea — have different cell membranes
The leakiness of the membrane allowed LUA to be powered by energy in its surroundings, most likely vents deep on the ocean floor, while holding in all the other components necessary for life. The team modeled how the membrane changed, enabling LUA’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
Bacteria and archaea share many common features such as genes, proteins and mechanisms of reading DNA, initially leading scientists to believe they were just different types of bacteria. Their classification changed in the 1970s after extreme differences were found in the way they replicate DNA and in the structure of their cell membrane. As they both stemmed from LUA, scientists set out to find answers in the structure and function of LUA’s membrane
Data from the study strongly suggest that LUA lived in the area where ancient seawater, dense with positively charged particles called protons, mixed with warm alkaline vent fluid, which contained few protons. The difference in the concentration of protons across these two environments enabled protons to flow into the cell, driving the production of a molecule called adenosine triphosphate (ATP) which powered the growth of cells, just as it does today. However, unlike modern cells the scientists believe this could only happen if the membrane was 'leaky', enabling protons to leave the cell spontaneously so more protons could enter to power growth
From a single basic idea, the model can explain the fundamental differences between bacteria and archaea. In these deep sea vents, there is a continuous flow of alkaline fluids, which mix with the ocean waters. When they mix, the fluids neutralize each other, and that stops any build-up of charge which would otherwise prevent protons flowing into the cell
If the first cells had leaky membranes, then protons could enter and then be neutralized, or leave again, almost as if there was no barrier at all
The mathematical modeling shows that the rate at which protons enter and leave was high enough to power the growth of cells via proteins embedded in the membrane. LUA could have been powered by natural proton gradients in vents, but only if it had a really leaky membrane, completely unlike today’s cells
The UCL researchers came to the conclusion using mathematical modeling, in which the findings were published on August 13, 2014, in PLOS Biology
Illustrated picture at http://cdn.phys.org/newman/gfx...
The study claims this membrane may explain why all cells use the same complex mechanism to harvest energy, and it may also explain why two types of fundamental single-celled organisms — bacteria and archaea — have different cell membranes
The leakiness of the membrane allowed LUA to be powered by energy in its surroundings, most likely vents deep on the ocean floor, while holding in all the other components necessary for life. The team modeled how the membrane changed, enabling LUA’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
Bacteria and archaea share many common features such as genes, proteins and mechanisms of reading DNA, initially leading scientists to believe they were just different types of bacteria. Their classification changed in the 1970s after extreme differences were found in the way they replicate DNA and in the structure of their cell membrane. As they both stemmed from LUA, scientists set out to find answers in the structure and function of LUA’s membrane
Data from the study strongly suggest that LUA lived in the area where ancient seawater, dense with positively charged particles called protons, mixed with warm alkaline vent fluid, which contained few protons. The difference in the concentration of protons across these two environments enabled protons to flow into the cell, driving the production of a molecule called adenosine triphosphate (ATP) which powered the growth of cells, just as it does today. However, unlike modern cells the scientists believe this could only happen if the membrane was 'leaky', enabling protons to leave the cell spontaneously so more protons could enter to power growth
From a single basic idea, the model can explain the fundamental differences between bacteria and archaea. In these deep sea vents, there is a continuous flow of alkaline fluids, which mix with the ocean waters. When they mix, the fluids neutralize each other, and that stops any build-up of charge which would otherwise prevent protons flowing into the cell
If the first cells had leaky membranes, then protons could enter and then be neutralized, or leave again, almost as if there was no barrier at all
The mathematical modeling shows that the rate at which protons enter and leave was high enough to power the growth of cells via proteins embedded in the membrane. LUA could have been powered by natural proton gradients in vents, but only if it had a really leaky membrane, completely unlike today’s cells