How does anaerobic respiration differ from aerobic respiration?

Anaerobic respiration differs from aerobic respiration as it occurs without the use of oxygen, producing less energy.

In more detail, both aerobic and anaerobic respiration are processes cells use to generate energy. However, they differ significantly in how they accomplish this task. Aerobic respiration, as the name suggests, requires oxygen to function. It is a three-step process that includes glycolysis, the Krebs cycle, and the electron transport chain. This process is highly efficient, producing up to 38 molecules of ATP (adenosine triphosphate), the cell's primary energy currency, from a single molecule of glucose.

On the other hand, anaerobic respiration does not require oxygen. It also begins with glycolysis, but instead of proceeding to the Krebs cycle and the electron transport chain, it undergoes either lactic acid fermentation or alcoholic fermentation. These processes regenerate the necessary NAD+ for glycolysis but produce far less ATP. In fact, anaerobic respiration only produces 2 ATP molecules per glucose molecule, making it much less efficient than aerobic respiration.

Another key difference is the by-products of each process. Aerobic respiration produces carbon dioxide and water, which are easily expelled from the body. However, anaerobic respiration can result in the build-up of lactic acid in muscles, which can cause discomfort and fatigue. In yeast cells, anaerobic respiration produces alcohol and carbon dioxide, which is why it's used in brewing and bread-making.

In summary, while both processes are essential for life, aerobic respiration is generally preferred due to its efficiency. However, in conditions where oxygen is scarce, such as intense exercise or in certain microorganisms, anaerobic respiration provides a vital alternative for energy production.