urea

Examples of urea in the following topics:

• Nitrogenous Waste in Terrestrial Animals: The Urea Cycle

  • Mammals, including humans, are the primary producers of urea.
  • The urea cycle is the primary mechanism by which mammals convert ammonia to urea.
  • Urea is made in the liver and excreted in urine.
  • The urea cycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea.
  • The urea cycle converts ammonia to urea in five steps that include the catalyzation of five different enzymes.

• Nitrogenous Waste in Birds and Reptiles: Uric Acid

  • Birds and reptiles have evolved the ability to convert toxic ammonia into uric acid or guanine rather than urea.
  • The animals must detoxify ammonia by converting it into a relatively-nontoxic form such as urea or uric acid .
  • The production of uric acid involves a complex metabolic pathway that is energetically costly in comparison to processing of other nitrogenous wastes such as urea (from the urea cycle) or ammonia; however, it has the advantages of reducing water loss and, hence, reducing the need for water.
  • Uric acid is also less toxic than ammonia or urea.
  • These include (a) ammonia, (b) urea, and (c) uric acid.

• Chemical Composition of Urine

  • The normal chemical composition of urine is mainly water content, but it also includes nitrogenous molecules, such as urea, as well as creatinine and other metabolic waste components.
  • Urea is essentially a processed form of ammonia that is non-toxic to mammals, unlike ammonia, which can be highly toxic.
  • Describe how normal urine consists of water, urea, salts and pigment

• Osmoregulators and Osmoconformers

  • However, the blood of sharks contains urea and trimethylamine oxide (TMAO).
  • The shark's blood electrolyte composition is not similar to that of seawater, but maintains isotonicity with seawater by storing urea at high concentrations.
  • Sharks are "ureotelic" animals that secrete urea to maintain osmotic balance.
  • TMAO stabilizes proteins in the presence of high urea levels, preventing the disruption of peptide bonds that would otherwise occur at such high levels of urea.

• Connecting Proteins to Glucose Metabolism

  • When the amino group is removed from an amino acid, it is converted into ammonia through the urea cycle.
  • In mammals, the liver synthesizes urea from two ammonia molecules and a carbon dioxide molecule.
  • Thus, urea is the principal waste product in mammals produced from the nitrogen originating in amino acids; it leaves the body in urine.

• Thermosetting vs. Thermoplastic Polymers

• Renal Disease and Failure

  • Renal failure uremia is a syndrome of renal failure characterized by elevated levels of urea and creatinine in the blood.
  • This is detected by a decrease in or absence of urine production or determination of waste products (creatinine or urea) in the blood.
  • Renal failure uremia is a syndrome of renal failure that includes elevated blood urea and creatinine levels.

• Preparation of 1º-Amines

  • Urea, the diamide of carbonic acid, fits this requirement nicely.
  • The resulting 3º-alkyl-substituted urea is then hydrolyzed to give the amine.

• Tubular Secretion

  • At this final stage it is only approximately one percent of the originally filtered volume, consisting mostly of water with highly diluted amounts of urea, creatinine, and variable concentrations of ions.

• Mole Fraction and Mole Percent

  • What is the mole fraction of cinnamic acid that has a mass percent of 50.00% urea in cinnamic acid?
  • The molecular weight of urea is 60.16 g/mol and the molecular weight of cinnamic acid is 148.16 g/mol.
  • This means that we have 50.0 g of urea and 50.0 g of cinnamic acid.
  • We have 0.833 moles urea and 0.388 moles cinnamic acid, so we have 1.22 moles total.