An experiment to determine the amount of urea in a specimen of urine.
Introduction.
Metabolism produces a number of toxic by-products, particularly the nitrogenous wastes that result from the breakdown of proteins and nucleic acids. Amino (NH2) groups are the result of such metabolic reactions and can be toxic if ammonia (NH3) is formed from them. Ammonia tends to raise the pH of bodily fluids and interfere with membrane transport functions. To avoid this the amino groups are converted into urea, which is less toxic and can be transported and stored to be released by the excretory system.
Urea is the result of two amino groups being joined to a carbonyl (C=O) to form CO(NH2)2, the process of which is called the ornithine cycle and takes place in the liver. The ornithine cycle was developed by Hans Krebs in 1932 and is similar to the Krebs cycle through the use of oxaloacetate. One of the steps in the cycle the breakdown of arginine into ornithine and urea, a reaction catalysed by the enzyme arginase. (See below)
(Fig 1.0)
Arginine Orthinine Urea
Urease is the enzyme which catalyses the hydrolysis of urea according to the following equation:
(NH2)2CO(aq) + 3H2O(l)  CO2(g) + 2NH3(g)
The acidic ammonium carbonate is formed because the carbon dioxide dissolves in water to produce carbonic acid (H2CO3), which immediately reacts with ammonia to form the ammonium carbonate. This is shown by the following equation:
2NH3(g) + H2CO3(aq)  (NH4+)2CO3(aq)
The resulting solution can then be titrated against hydrochloric acid with methyl orange as the indicator in order to determine how much urea was present initially.
The point of neutralisation using a methyl orange indicator is determined using the following colour changes.
 Acid  Red.
 Neutral  Yellow.
 Alkali  Orange.
Enzymes are nearly all made up of globular proteins. The structure of enzymes can be divided into three categories:
1. The primary structure, which is the sequence of amino acids.
2. The secondary structure, which is the coiling of the protein into an alpha helix
3. The tertiary structure, which is the 3D shape into which the protein is folded. This shape gives the enzyme its properties and specificity. The shape is held together by ionic bonds, disulphide bridges and the weaker hydrogen bonds.
Method.
Six urea solutions were prepared an placed in conical flasks one of which was of unknown concentration. The flasks were sealed to prevent CO2 and NH3 gases from escaping and then placed in a water bath at 35oC for 1 hour.
When this substrate fits into the active site, it forms an enzyme-substrate complex. This means that an enzyme is specific. The bonds that hold enzymes together are quite weak and so are easily broken by conditions that are very different when compared with their optimum conditions. When these bonds are broken the enzyme, along with the active site, is deformed, thus deactivating the enzyme. This is known as a denatured enzyme.
The major sites for the production of ammonia are the intestines, liver, and kidneys. It is biosynthesized through normal amino acid metabolism. The kidneys generate ammonia from glutamine by the actions of renal glutaminase and glutamate dehydrogenase. Ammonia is formed from urea by the action of bacterial urease in the lumen of the intestine, which is absorbed from the intestine by the portal vein. Amines obtained from diet and monoamines that serve as neurotransmitters or hormones can create ammonia by action of amine oxidase. In purine and pyrimidine catabolism, amino groups attached to the rings are released as ammonia.
Furthermore, an additional method to use other hydrochloric acids that have different concentration levels such as 1 M and 2.5 M ones, can improve the outcome of the results. This increases the variation of the independent variable, which accordingly increases the precision of results.
The three-dimensional contour limits the number of substrates that can possibly react to only those substrates that can specifically fit the enzyme surface. Enzymes have an active site, which is the specific indent caused by the amino acid on the surface that fold inwards. The active site only allows a substrate of the exact unique shape to fit; this is where the substance combines to form an enzyme- substrate complex. Forming an enzyme-substrate complex makes it possible for substrate molecules to combine to form a product. In this experiment, the product is maltose.
4. Take matrix ruler and lay test tubes and mark from the bottom at 4cm, 5cm and 6cm 5. Fill each test tubes to the 4-cm mark with the respective pH buffer (2,4,6,7,8, and 10) 6. Add more 1cm (up to 5 cm mark) of potato extract containing catechol oxidase and swirl to mix. 7.
Determining the Concentration Of Limewater Solution Aim: The aim of this experiment is it to find out the concentration of Limewater by performing a titration with hydrochloric acid which has concentration exactly 2.00M.. What is required for me is that I have to design my own experiment and chose the right and appropriate apparatus and equipment. I will be provided with 250cm3 of limewater, which has been made to which contains approximately 1g/dm3 of calcium Hydroxide. This hypothesis from www.studentcentral.co.uk We were also give Hydrochloric acid (HCl) with a concentration of 2.00 mol/dm3 normal laboratory apparatus was also given and so was an indicator.
Tertiary structure- this is where the Haem group of the polypeptide chains cause it to twist and fold to form the first 3D structure a structure for haemoglobin.
Domains may be considered to be connected units, which are to varying extents independent in terms of their structure, function and folding behaviour. Each domain can be described by its fold. While some proteins consist of a single domain, others consist of several or many. A number of globular protein chains consist of two or three domains appearing as 'lobes'. In other cases the domains may be of very different nature- for example some proteins located in cell membranes have a globular intracellular or extracellular domain distinct from that which spans the membrane.
Enzymes are protein molecules that are made by organisms to catalyze reactions. Typically, enzymes speeds up the rate of the reaction within cells. Enzymes are primarily important to living organisms because it helps with metabolism and the digestive system. For example, enzymes can break larger molecules into smaller molecules to help the body absorb the smaller pieces faster. In addition, some enzyme molecules bind molecules together. However, the initial purpose of the enzyme is to speed up reactions for a certain reason because they are “highly selective catalysts” (Castro J. 2014). In other words, an enzyme is a catalyst, which is a substance that increases the rate of a reaction without undergoing changes. Moreover, enzymes work with
Enzymes are essential biological catalysts in the human body that biochemical reaction. Catalysts work by lowering the activation energy, the minimum energy required for a reaction to occur, which increases the rate of the reaction (Burdge, 2014). Enzymes catalyze reactions by applying pressure onto the bonds of the substrate which lowers the activation energy and breaks these bonds to form products. Even though some enzymes have been found to be non-proteins, most of them are globular proteins which possess an active site where the substrate attaches itself (Raven, 114). The two models that describe the manner in which substrates attach to enzymes are the lock-and-key model and the induced fit model. The lock-and-key model is used to explain an enzyme that fits to only one type of substrate. It is like a lock and key in the sense that only one lock can fit into a key, therefore, only one substrate can fit into the active site of an enzyme that follows this model. On the other hand, an enzyme that follows the induced fit model slightly changes its shape in order for the substrate to...
In essence, the main objective was to use chemical titration to measure and then calculate the rate of conversion of hydrogen peroxide (H2O2) to water and oxygen by using the enzyme catalase. Other purposes of the lab were; to measure the effects of changes of temperature, pH, enzymes concentration, and substrate concentration on rates of an enzyme. The lab was also an opportunity to see a catalyzed reaction in a controlled experiment. And the last objective was to learn how environmental factors affect the rate of enzyme catalyzed reactions.
For this experiment we used titration to standardize the exact concentration of NaOH. Titration is the process of carefully adding one solution from a buret to another substance in a flask until all of the substance in the flask has reacted. Standardizing is the process of determining a solutions concentration. When a solution has been standardized it is referred to as a standard solution. To know when a solution is at its end point an indicator is added to acidic solution. An indicator is an organic dye that is added to an acidic solution. The indicator is one color is in the acidic solution and another color in the basic solutions. An end point occurs when the organic dye changes colors to indicate that the reaction is over (Lab Guide pg. 141).
produced during glycolysis as the phosphate source. The products of the reaction are glucose 6-phosphate and pyruvate (PYR). The phosphorylated glucose is
First type of biogeochemical cycle is nitrogen cycle. Nitrogen is abundant and chemically inert gases, constitutes of about 78% of the atmosphere. According to Stevenson and Cole (1999), accumulation in soil happens through microbial fixation of nitrogen in the presence of ammonia, nitrate and nitrite; depletion exists in the process of crop removal, leaching and volatilization. In term of that, the process of releasing compound during decomposition is called mineralization. Mineralization process is carried out by the microorganisms in which it releases carbon, and also ammonium (Sprent, 1987). As a result, many kinds of organic reduce nitrogen present, like urea, organic bases, such as purines and pyrimidines, and amino compounds. Animals have nitrogenous wastes and will eventually produce lots of nitrogen (Sprent, 1987). Several pathways are illustrated throughout the nitrogen cycle, such as nitrogen fixation, ammonification, nitrification and denitrification. Gates (1921) stated that the process of converted gaseous nitrogen into ammonia or ammonium is nitrogen fixation, while ammonium can also be produced through the decaying of nitrogenous organic substance, which is called ammonification. Afte...
In the liver and muscles, glycogen is produced from glucose by glycogenesis. Glycogen is stored in the liver and muscles glucose levels are low. When blood glucose levels are low, epinephrine and glucagon are secreted stimulating the conversion of glycogen to glucose (glycogenolysis). If there is an immediate need for energy upon glucose entering the cell, then glycoysis usually takes place. The end products of glycolysis are pyruvic acid and ATP. Since glycolysis releases small amounts ATP, further reactions continue to convert pyruvic acid to acetyl CoA and then citric acid in the citric acid cycle. The majority of the ATP is made from oxidations in the citric acid cycle in connection with the electron transport chain (3). This is how normal glucose metabolism takes place (figure-1).