The Urea Cycle The ornithine cycle (also known as the 'urea cycle ') is a cycle of biochemical reactions occurring in many animals that produce urea ((NH2)2CO) from ammonia (NH3). This cycle was the first metabolic cycle discovered by Hans Krebs and Kurt Henseleit in 1932, five years before the discovery of the TCA cycle. In mammals, the urea cycle takes place primarily in the liver, and to a lesser extent in the kidney. Ammonia Toxicity Every amino acid contains at least one amino group. Therefore every amino acid degradation pathway has a key step where the amino group is removed.
Ornthine is then carried back in the mitochondrial matrix and the cycle is complete. There are two nitrogens in urea. One nitrogen came from the ammonia produced in the mitochondrial matrix captured in the form of carbamoyl phosphate. The second nitrogen came from the α−amino group of the aspartate substrate in the reaction involving argininosuccinate synthetase. The carbon of the bicarbonate was the sole carbon of urea.
Reduction iii. Dehydration iv. Reduction For fatty acid synthesis to begin, malonyl-CoA must be present. So the first committed step of this pathway is the carboxylation of acetyl CoA to malonyl-CoA catalyzed by acetyl CoA carboxylase. This reaction is shown below: After the production of malonyl-CoA, fatty acid biosynthesis proceeds in the following steps: 1) Transfer of acetyl group form acetyl CoA to acyl carrier protein (ACP) by the enzyme, acetyl CoA-ACP transacylase.Similarly, malonyl group of mallonyl-CoA is transferred to ACP by malonyl CoA-ACP transacylase.
Pyruvate can be metabolized into neutral compounds such as acetoin, 2-3 butylene glycol, and diacetyl. [2 pyruvate -> acetoin + 2CO2 ; acetoin + NADH + H+ -> 2,3-butanediol + NAD+] “In the presence of alkali (KOH) and atmospheric oxygen, acetyl methyl carbinol is oxidized to diacetyl, a reaction which is catalyzed by alpha- naphthol. Diacetyl formed reacts with guanidine-containing compounds such as arginine contributed by peptone in the medium, to form a red colored product. The resultant red color is indicative of a positive VP test.” (Pradhan, 2014) In both cultures, there is no red coloration observed (see Figure 11.6 and 11.7), thus Micrococcus luteus and the unknown microbe are both unable to produce acetoin via butanediol
Carnitine is mainly introduced to the body in the diet through meat and dairy products. Carnitine can also be produced in the body. It is usually synthesised using the amino acids lysine and methionine. Though carnitine in human tissues is found in free and esterified forms, free carnitine (L Carnitine) occupies approximately 80% of total carnitine levels in these tissues under normal conditions. L Carnitine has many functions in the body.
The Renin-Angiotensin System Renin is synthesized and stored in an inactive form called prorenin in the juxtaglomerular cells of the kidneys. These cells are modified smooth muscle cells located in the walls of the afferent arterioles. When the arterial pressure falls, intrinsic reactions in the kidneys themselves cause many of the prorenin molecules in the JG cells to split and release renin. Most of the renin enters the renal blood and then passes out of the kidneys to circulate throughout the entire body .
It turns NADH and pyruvate produced in glycolysis into NAD+ and an organic molecule and with the presence of O2, NADH and pyruvate are used to generate ATP in respiration.Fermentation also change food smell and flavour which might be can accepted by consumer. Fermentation does not necessarily have to be carried out in an anaerobic environment. Sugars are the most common substrate of fermentation, and typical examples of fermentation products are ethanol, lactic acid, carbon dioxide, and hydrogen gas (H2). However, more exotic compounds can be produced by fermentation, such as butyric acid and acetone. This is called oxidative phosphorylation.
Urinogenital system comprises urinary system and reproductive system. Urinary system – * The urinary system is the body’s waste removal system. The kidneys' main function is to process and remove wastes (created from cell metabolism) and excess ions from the blood, regulate blood volume and maintain electrolyte balance. The urinary system consists of paired kidneys and ureters. Kidneys – *Kidneys are metanephric and paired.