Phenylketonuria (PKU) can be defined as a rare metabolic disorder caused by a deficiency in the production of the hepatic (liver) enzyme phenylalanine hydroxylase (PAH). PKU is the most serious form of a class of diseases referred to as hyperphenylalaninemia, all of which involve above normal (elevated) levels of phenylalanine in the blood.
All organisms carry out cellular respiration (except viruses) - it is the basic process which supports life as we know it. Viruses, on the other hand, are not always câ¦onsidered to be living, one of the reasons being that they do NOT carry out cellular respiration.
ATP, a high energy molecule, is expended by working cells. Cellular respiration occurs in both eukaryotic and prokaryotic cells. There are three main stages of cellular respiration: glycolysis, the citric acid cycle, and electron transport/oxidative phosphorylation. Glycolysis. Glycolysis literally means splitting sugars. Glucose, a six carbon sugar, is split into two molecules of a three carbon sugar. Glycolysis takes place in the cell's cytoplasm. Glucose and oxygen are supplied to cells by the bloodstream. In the process of glyoclysis, two molecules of ATP, two molecules of pyruvic acid and two high energy electron carrying molecules of NADH are produced. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of aerobic cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called anaerobic respiration or fermentation.