The Electron Transport Chain has five complexes. These are comprised of a number of subunits. What I find particularly interesting is that some of the proteins are generated via nuclear DNA and some of the proteins are generated via mitochondrial DNA. Most of the ROS (that damages mtDNA) is generated by Complexes 1 and 3. Complex 1 has 45 subunits in humans, but in fact only 7 of those (ND1, ND2, ND3, ND4, ND4L, ND5, ND6) are encoded by the mitochondrial genome. Complex 3, however, has 11 subunits only 1 of which is in mtDNA (MT-CYB) Complex 2 is entirely coded by the nucleus, Complex 4 has 3 (MT-CO1, MT-CO2, and MT-CO3) out of 13 units coded in mtDNA. ATP Synthase also called Complex 5 has 16 units two of which are encoded in the mitochondria. Hence it is clear that complex 1 is perhaps the key complex for mtDNA mutation linked aging and not surprising that this is the complex inhibited in Oocytes. There is an argument that for hydrophobic subunits the energy cost of transferr...
Oxygen is essential for human life. That is well known. However, the level of Oxygen in the atmosphere has interesting effects. I wrote previously about The Hypoxia Inducible Factor (HIF). HIF (particularly 1 alpha) is a molecule which signals cells to create proteins to build in response to stress. This can involve building new mitochondria or recycling old inefficient mitochondria. In essence it is ringing an alarm that calls for cells to get better prepared for stress. Interestingly HIF is switched on by a drop in the oxygen partial pressure (that proportion of air pressure that is oxygen). It is also well known that if brain cells get too little Oxygen then they can get harmed or die. Hence too low an Oxygen level causes brain damage. In fact there is evidence from people living at high altitudes that at a point the oxygen level is too low and this harms health. However, there is another aspect of Oxygen levels that relates to the mitochondria. The mitochondria produc...