During aerobic respiration, electrons travel downhill in which of these sequences?
food-Krebs cycle-ATP-NAD+ or Food-NADH-electron transport chain-oxygen
If I could figure out what it ends with it would be easier to answer.
But I believe the correct answer is Food-NADH-electron transport chain-oxygen.
To determine the sequence of electron flow during aerobic respiration, we need to understand the process.
During aerobic respiration, electrons from the breakdown of food molecules are passed through a series of electron carriers in a process known as the electron transport chain (ETC). Here is how the sequence goes:
1. Food molecules (such as glucose) are broken down through a series of chemical reactions called the Krebs cycle (also known as the citric acid cycle or the TCA cycle) within the mitochondria of the cells. This process generates a small amount of ATP (adenosine triphosphate) and high-energy electron carriers, mainly NADH.
2. The high-energy electrons carried by NADH are then transported to the electron transport chain, which is located in the inner mitochondrial membrane. The electrons are transferred to a series of protein complexes (enzyme complexes) in the electron transport chain.
3. As the electrons pass through these protein complexes, energy is released and used to pump hydrogen ions (H+) across the inner mitochondrial membrane, creating an electrochemical gradient.
4. Finally, the electrons, along with hydrogen ions, combine with oxygen (O2) at the end of the electron transport chain to form water (H2O), which acts as the final electron acceptor. This represents the terminal step of electron flow during aerobic respiration.
Based on this information, the correct sequence of electron flow during aerobic respiration is:
Food-NADH-electron transport chain-oxygen.
Therefore, the second option you provided, "Food-NADH-electron transport chain-oxygen," is the correct sequence.
During aerobic respiration, electrons travel downhill in the following sequence:
Food → NADH → Electron transport chain → Oxygen.