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.
1) In the blood, oxygen is carried by the red blood cells as oxyhemoglobin (this is just oxygen bonded to hemoglobin). 2) At the body cells, this oxygen leaves the hemoglobin by easily diffusing through the capillaries. 3) The cells can now carry out cellular aerobic respiration at the mitochondria for energy.