Her er en interessant lenke om aminosyrer http://www.nutritionreview.org/library/krebs.php
All cells must produce energy to survive. Hans A. Krebs first elucidated the process of cells converting food into energy, the Citric Acid Cycle, in 1937. Krebs proposed a specific metabolic pathway within the cells to account for the oxidation of the basic components of food – carbohydrates, protein and fats – w for energy. The Krebs’ cycle takes place inside the mitochondria or 'power plant' of cells and provides energy required for the organism to function.

Mitochondria are found in all cells in the human body, with the exception of mature red blood cells. The primary function of these tiny organelles (each cell contains between 500 and 2,000 mitochondria) is to convert energy found in nutrient molecules and store it in the form of adenosine triphosphate (ATP). ATP is the universal energy-yielding molecule used by enzymes to perform a wide range of cellular functions. Humans cannot survive, even for a second, without a constant supply of ATP.