This proves that the Krebs cycle occurs in the oxidation of fats. It was later found by Krebs that the citric acid cycles is not limited to animal cells but it takes place is almost all aerobic cells. In a cell, the Krebs cycle occurs in the mitochondria or power plant and generated energy need by the organism to function (The Krebs Cycle. Cell Structure and Function).
Krebs metabolic pathway in the cells is responsible for the oxidation of the basic food components that constitute carbohydrates, protein and fat to give out energy. Mitochondria are present in the cells of the human body. The fundamental function of these minute organelles (that range from 500 to 2000 mitochondria in a cell) is to convert energy present in the nutrient molecules and store this energy in the form of ATP (adenosine triphosphate). ATP is the universal energy producing molecules utilised by enzymes to conduct a number of cellular functions. Human being cannot live even for a second without the continuous supply of ATP. Energy conversion requires oxygen and this is supplied by the circulatory and respiratory systems which carry the oxygen to the tissue for further use by mitochondria to remove carbon dioxide. This process is called cellular respiration. During the Krebs cycle, acetyl coenzyme A is metabolised into citric acid which undergoes a complex series of biological oxidation to produce free hydrogen ions. The hydrogen ion then move to a biochemical phase called oxidative phosphorylation which is a highly competitive aerobic energy producer. Oxidative phosphorylation produces 36 molecules of ATP.
There are different phases at which metabolites move into the Krebs cycle. Components of carbohydrates, fat and protein are broken down to molecule coenzyme A before moving into the Krebs cycle. Glucose the basic fuel in the body is initially metabolized into pyruvic acid and later to acetyle