Cellular Respiration

Aerobic respiration, anaerobic respiration, glycolysis, Krebs cycle, basal metabolic rate, fermentation

⁣Cellular respiration is the process by which cells convert nutrients into energy in the form of ATP (adenosine triphosphate). It is a series of metabolic reactions that occur in the presence of oxygen (aerobic respiration) or in the absence of oxygen (anaerobic respiration).

In aerobic respiration, the process takes place in the mitochondria and consists of three main stages: glycolysis, the Krebs cycle (also known as the citric acid cycle or TCA cycle), and the electron transport chain.

Glycolysis occurs in the cytoplasm and breaks down glucose into two molecules of pyruvate. This process yields a small amount of ATP and NADH.

Next, pyruvate enters the mitochondria where it undergoes the Krebs cycle. During this cycle, pyruvate is further broken down, releasing carbon dioxide and producing NADH, FADH2, and ATP.

The final stage is the electron transport chain, which occurs in the inner mitochondrial membrane. NADH and FADH2 produced in previous stages donate electrons to the chain, creating a flow of electrons that generates a proton gradient. This gradient drives ATP synthesis through oxidative phosphorylation.

Anaerobic respiration occurs in the absence of oxygen and includes processes such as alcoholic fermentation and lactic acid fermentation. These processes allow cells to continue generating small amounts of ATP without oxygen but are less efficient than aerobic respiration.

Overall, cellular respiration is a crucial process for organisms to obtain energy from nutrients and sustain various cellular activities.