Final answer:
Complex I, also known as NADH dehydrogenase, is the large enzyme complex involved in transferring two electrons via NADH and pumping hydrogen ions across the membrane, which is essential for ATP production in the electron transport chain during cellular respiration.
Step-by-step explanation:
The student is asking about the large enzyme complex responsible for carrying out multiple steps in a biochemical reaction. The answer to this question is Complex I, which is also known as NADH dehydrogenase. This complex is a crucial part of the electron transport chain, which is a series of reactions that are vital for the generation of ATP, the cellular currency of energy, during cellular respiration. Complex I begins the process by transferring two electrons via NADH, and it is made up of flavin mononucleotide (FMN) and an iron-sulfur (Fe-S) containing protein. This complex not only initiates the electron transfer but also helps in pumping hydrogen ions across the membrane, therefore maintaining a hydrogen ion gradient important for ATP production.