Question

. There are three stages of cellular respiration in the presence of oxygen. (a) Identify similarities between the first two stages of cellular respiration. (b) Explain why the presence of oxygen is so important at the completion of the last stage of cellular respiration.

Write your response below.

Answer 1

Cellular respiration uses energy in glucose to make ATP.Aerobic (“oxygen-using”) respiration occurs in three stages: glycolysis, the Krebs cycle, and electron transport.

(a). Similarities between glycolysis and Kreb's cycle are:

• Glycolysis and TCA cycle consists of series of enzyme catalyzed reactions.
• In both processes, substrate level phosphorylation takes place.
• Both processes produce NADH, H2O as products.
• Both processes are regulated through hormonal control, allosteric regulation and end product inhibition (feedback mechanisms).

(b).In cellular respiration, oxygen is the final electron acceptor. Oxygen accepts the electrons after they have passed through the electron transport chain and ATPase, the enzyme responsible for creating high-energy ATP molecules. The electron transport chain produces 34 ATP. The electron transport chain occurs across the inner membrane of the mitochondria. The electron transport chain requires oxygen. If there is no oxygen to accept electrons, then the electron transport chain stops working and the high energy molecules NADH+H and FADH2 cannot be converted back into NAD and FAD.