The Krebs cycle produces electron carrier molecules. Where do these carrier molecules deliver the electrons produced in the Krebs cycle?
a
alcohol fermentation
b
lactic acid fermentation
c
glycolysis
d
the electron transport chain
d) the electron transport chain
The electron carrier molecules produced in the Krebs cycle deliver the electrons to the electron transport chain (option d). The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane (in eukaryotes) or the plasma membrane (in prokaryotes). These carrier molecules, including NADH and FADH2, transfer the electrons to the electron transport chain, where they are used to generate ATP through oxidative phosphorylation. This process is the final step in aerobic cellular respiration.
The electron carrier molecules produced in the Krebs cycle deliver the electrons to the electron transport chain. To understand why, let's first discuss the Krebs cycle and the electron transport chain.
The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a series of chemical reactions that occurs in the mitochondria of cells. It oxidizes acetyl CoA, a molecule derived from the breakdown of carbohydrates, fats, and proteins. In this process, carbon dioxide is released, and several energy-rich molecules, such as NADH and FADH2, are produced as electron carriers.
Now, the electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. Its main role is to transfer electrons from the electron carriers, NADH and FADH2, to molecular oxygen (O2). This transfer of electrons generates ATP, the energy currency of cells. The movement of electrons through the electron transport chain creates a proton gradient across the inner mitochondrial membrane, which is then used to produce ATP through a process called oxidative phosphorylation.
So, to answer your question, the electron carrier molecules produced in the Krebs cycle, such as NADH and FADH2, deliver their electrons to the electron transport chain. The electron transport chain utilizes these electrons to facilitate the production of ATP through oxidative phosphorylation. Therefore, the correct answer is d) the electron transport chain.