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.
Energy is defined as the ability to do work. Cellular respiration provides energy for living organisms. So, cellular respiration is important because it provides the energy for living organisms to perform all of the other necessary functions to maintain life. Most single-celled organisms, such as bacteria, do not require much energy and are able to survive on glycolysis and fermentation.