Without oxygen, cellular respiration grinds to a standstill, although glycolysis can continue to make some ATP anaerobically for a short time. When oxygen runs out, why does electron transport stop? Why do you thing the Krebs cycle stops?
When oxygen runs out, electron transport stops because it serves as the final electron acceptor in the electron transport chain (ETC). The ETC is an essential part of cellular respiration and occurs in the inner membrane of the mitochondria.
During cellular respiration, electrons are passed through a series of protein complexes in the ETC, ultimately leading to the reduction of oxygen to water. This electron flow generates a proton gradient across the inner mitochondrial membrane, which drives the synthesis of ATP. Without oxygen, the ETC cannot transfer electrons to the final acceptor, resulting in a halt of electron transport and the subsequent ATP production.
As for the Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle (TCA cycle), it relies on the availability of oxygen indirectly. The Krebs cycle is an aerobic process that takes place in the mitochondrial matrix, where acetyl-CoA molecules derived from the breakdown of carbohydrates, fats, and proteins enter the cycle.
The primary role of the Krebs cycle is to generate high-energy molecules, such as NADH and FADH2, which serve as electron carriers for the electron transport chain. Without a continuous supply of oxygen, the Krebs cycle stalls because the electron carriers NAD+ and FAD cannot be effectively regenerated, hindering the cycle's ability to produce energy-rich molecules.
In summary, both electron transport and the Krebs cycle stop when oxygen runs out because the former relies on oxygen as the final electron acceptor, while the latter indirectly depends on oxygen for the regeneration of electron carriers necessary for its function.
When oxygen runs out, electron transport chain (ETC) stops because it relies on oxygen as the final electron acceptor. The main function of ETC is to transfer electrons from NADH and FADH2 to oxygen, which facilitates the production of ATP through oxidative phosphorylation. Oxygen acts as the final electron acceptor in this process, creating a gradient across the mitochondrial inner membrane that drives the synthesis of ATP.
Without oxygen, electrons cannot flow through the ETC, leading to a halt in the transfer of electrons and a disruption in the proton gradient. As a result, ATP synthesis through oxidative phosphorylation cannot occur, and the majority of ATP production comes to a standstill.
Similarly, the Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid (TCA) cycle, is closely linked to the ETC. It serves as the major provider of electron carriers (NADH and FADH2) that enter the ETC. The Krebs cycle begins with the oxidation of acetyl-CoA and generates electron carriers along with releasing carbon dioxide.
When oxygen is depleted, the Krebs cycle slows down because its primary purpose is to generate electron carriers used in the ETC, where these carriers get oxidized. With the ETC being unable to accept these electrons due to the lack of oxygen, the Krebs cycle gradually stops as there is no demand for further electron carriers.
In summary, both the electron transport chain and the Krebs cycle stop when oxygen runs out because the ETC depends on oxygen as the final electron acceptor, and the Krebs cycle relies on the ETC to utilize its electron carriers. Without oxygen, these crucial processes cannot function properly, leading to a decrease in ATP production.