Dr. Mark Tarnopolsky explains how a purple bacterium entered an early cell 1.5 billion years ago and became the mitochondria. This allowed cells to handle toxic oxygen and produce energy far more efficiently than before. Over time, about 1,500 mitochondrial genes moved into the cell's nucleus.
About 1.5 billion years ago.
Some 1,500 proteins.
January 14, 2011.
But the hypothesis is that about 1.5 billion years ago, when the oxygen content of the environment was going up, we took on this endosymbiotic relationship, where what was thought to be probably a purple photosynthetic type of bacteria invaded what at the time was called a proto eukaryotic cell, which then went on to form the eukaryotes, of which we have the eukaryotic cells throughout our body. And what they think is that as the oxygen content went up, these mitochondria, which were bacteria, allowed us to detoxify the oxygen in our environment so that we weren't producing as many free radicals. But probably more importantly, it allowed us to extract more energy from our food. One of the first energy pathways that we had were the anaerobic pathways, such as the breakdown of sugar through glycolysis, which is rather energy inefficient. So in the mitochondria, we can use fats, proteins and carbohydrates in the presence of oxygen to extract much more ATP, or units of energy per gram of protein, carbohydrate and fat. And what's interesting is that throughout evolution, the some 1500 proteins that make up a mitochondria are now encoded for by our nucleus. So through this evolutionary process, the blueprints, if you will, to make this little engine for our cell were transferred to the nucleus.
