1. From one molecule of glucose, which process generates the largest amount of ATP?
a. Glycolysis in a prokaryotic cell under aerobic conditions
b. Glycolysis in a eukaryotic cell
c. the TCA (Krebs) cycle in a prokaryotic cell
d. the TCA (Krebs) cycle in a eukaryotic cell
e. the electron transport chain in a eukaryotic cell
The answer is e.
e. the electron transport chain in a eukaryotic cell
To determine which process generates the largest amount of ATP from one molecule of glucose, we need to understand the process of cellular respiration. Cellular respiration is the metabolic process by which living cells convert glucose into ATP, the energy currency of cells.
Let's examine each option to see which one generates the most ATP:
a. Glycolysis in a prokaryotic cell under aerobic conditions:
Glycolysis is the first step of cellular respiration, occurring in the cytoplasm of the cell. During glycolysis, one molecule of glucose is metabolized to produce two molecules of pyruvate, a net gain of 2 ATP, and 2 NADH. However, since this process occurs in a prokaryotic cell under aerobic conditions, we need to account for the additional steps in cellular respiration.
b. Glycolysis in a eukaryotic cell:
Similar to glycolysis in prokaryotic cells, glycolysis in eukaryotic cells also yields a net gain of 2 ATP molecules. However, eukaryotic cells have additional stages in cellular respiration that can further contribute to ATP production.
c. The TCA (Krebs) cycle in a prokaryotic cell:
The TCA cycle, also known as the Krebs cycle, occurs in the mitochondria of eukaryotic cells and the cytoplasm of prokaryotic cells. It is the second stage of cellular respiration. The TCA cycle produces ATP through the oxidation of pyruvate derived from glycolysis. While the TCA cycle generates some ATP, it is not the primary ATP producer in cellular respiration.
d. The TCA (Krebs) cycle in a eukaryotic cell:
In eukaryotic cells, the TCA cycle occurs in the mitochondria. During the cycle, remaining carbon atoms from glucose are oxidized further, releasing electrons that can be harvested in subsequent steps to produce more ATP. The TCA cycle produces ATP directly through substrate-level phosphorylation and indirectly through the production of NADH and FADHâ‚‚, which enters the electron transport chain (ETC) to generate ATP.
e. The electron transport chain in a eukaryotic cell:
The ETC is the final stage of cellular respiration. It takes place in the inner mitochondrial membrane of eukaryotic cells. The NADH and FADHâ‚‚ generated in previous steps, including glycolysis and the TCA cycle, donate electrons to the ETC. As the electrons move through the ETC, energy is released, which is used to pump protons across the membrane. This creates a proton gradient, and as the protons flow back through ATP synthase, ATP is produced. The ETC is responsible for the majority of ATP production in cellular respiration.
Considering the options given, the electron transport chain in a eukaryotic cell (option e) generates the largest amount of ATP from one molecule of glucose. It is the final step in cellular respiration and is responsible for producing the majority of ATP.