Cellular respiration

Cellular respiration is the process by which animals convert food into energy for their cells to use. This energy is stored in a molecule called adenosine triphosphate (ATP), which is the cell's primary energy currency. Cellular respiration is an important process that provides the energy needed for various cellular functions, including muscle contraction, protein synthesis, and nerve impulse transmission. It is essential for life and for maintaining cellular homeostasis.

The first step of cellular respiration is called glycolysis and results in the formation of pyruvate.

There are two types of pathways for cellular respiration to continue. One is Aerobic cellular respiration, which occurs when oxygen is present, and pyruvate will enter the Krebs cycle, allowing the electron transport chain to proceed. The other is Anaerobic cellular respiration, which does not require the presence of oxygen, and pyruvate will undergo lactic acid fermentation. Comparing the results of aerobic and anaerobic respiration highlight why oxygen is important for cellular respiration.

Diagram showing cellular respiration steps. Within a cell, carbohydrates are broken down to glucose. Glucose undergoes glycolysis to produce pyruvate, which enters the mitochondria. In the presence of oxygen, aerobic respiration proceeds. The pyruvate becomes acetyl Co A and enters the Krebs cycle. Krebs cycle products carry over to the electron transport chain, where oxygen is the final electron receptor. NADH produced during glycolysis also enters the electron transport chain. In the absence of oxygen, pyruvate undergoes fermentation to produce lactic acid, which builds up in the cell.

Figure 1: Cellular respiration steps.

Cellular respiration is the process that converts the energy from chemical bonds in food to a form of energy that the cell can use, ATP.