Sejtlégzésben

Sejtlégzésben, often translated as cellular respiration, is a fundamental metabolic process that occurs within the cells of living organisms. This process is responsible for converting biochemical energy from nutrients into adenosine triphosphate (ATP), and then releasing waste products. ATP is the main energy currency of the cell, powering most cellular activities.

The primary molecules involved in cellular respiration are glucose, a sugar, and oxygen. In eukaryotes, cellular respiration typically begins with glycolysis, which takes place in the cytoplasm. Glycolysis breaks down glucose into pyruvate, a smaller molecule. This initial step yields a small amount of ATP.

Following glycolysis, if oxygen is present, the pyruvate molecules enter the mitochondria, the powerhouses of the cell. Here, through a series of complex reactions including the Krebs cycle (also known as the citric acid cycle) and oxidative phosphorylation, the remaining energy from the original glucose molecule is extracted. Oxidative phosphorylation, in particular, is where the majority of ATP is generated, using a proton gradient and the enzyme ATP synthase.

The waste products of cellular respiration are carbon dioxide and water. Carbon dioxide is released from the cell, and in multicellular organisms, it is expelled from the body. Water is also a byproduct and can be reused by the cell or excreted. In the absence of oxygen, cells can resort to anaerobic respiration or fermentation, which produce less ATP but allow survival under oxygen-deprived conditions. This process is vital for the survival and functioning of almost all known living organisms.