Final answer:
The molecules that deliver electrons to the electron transport chain are NADH and FADH2, which help establish a proton gradient for ATP synthesis. ATP is not an electron donor, and O2 serves as the final electron acceptor, not a source. Therefore, the correct answers are FADH2 and NADH.
Explanation:
Electron Transport Chain and Energy Production
The electron transport chain (ETC) is a critical component of cellular respiration, specifically during oxidative phosphorylation. It occurs in the inner mitochondrial membrane and is responsible for the production of ATP through the establishment of a proton gradient.
Key Molecules Delivering Electrons
In this context, the following molecules are vital:
- NADH: This molecule is produced during glycolysis and the Krebs cycle, and it donates electrons to the ETC, facilitating the transport of protons (H+) across the mitochondrial membrane.
- FADH2: Similar to NADH, FADH2 also donates electrons to the ETC, contributing to the generation of the proton gradient, but at a different point than NADH, which affects the total ATP yield.
The other options:
- ATP is the main energy currency of the cell, but it does not participate in delivering electrons to the ETC.
- O2 is the terminal electron acceptor in the electron transport chain, but it does not deliver electrons itself.
Thus, the correct answers to the question are FADH2 and NADH.
Learn more about electron transport chain here:
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