The objective of this experiment is to identify macromolecules by examining the chemical changes and analyzing the results based on the properties of known solutions and macromolecules. This lab, identifying organic macromolecules, focuses primarily on the colour changes of the solutions and the molecular changes that lead to these physical changes.
Iodine Test
Two common polysaccharides, starch and glycogen, serve as energy storage molecules in plants and animals respectively. Starch consists of two major polysaccharides: amylose and amylopectin, both of which are composed of chains of D-glucose units joined by α-1, 4-glycosidic bonds. While amylose has an unbranched helical structure, amylopectin is highly branched with α-1, 6-glycosidic bonds joining the branches at the branch points. Amylopectin can be found in both starch and glycogen (Brown & Poon, 2014). The technique that will
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In the iodine test, Lugol’s solution containing iodine and potassium iodide will serve as the indicator. This test is chosen for determining the presence of starch or glycogen because the amylose in starch reacts with iodine and forms a dark blue complex – the amylose-iodine complex. The complex is formed by iodine atoms fitting into the linear helical chain of amylose, increasing the chain length. The wavelength of maximum absorption is in turn increased because the reaction changes the energy level spacing, giving the complex a blue black colour (Rundle & Foster & Baldwin, 1944). Similarly, the reaction between glycogen and iodine also produces a red-brownish colour which is less intense than amylose’s blue black. This
The product ratio of N-ethylsaccharin to O-ethylsaccharin that occurred due to alkylation with iodoethane at 80 oC was determined to be 81.5% to 18.5%, respectively, based on an analysis of the 1H NMR spectrum that was collected. The melting point range of 87.8-94.7 oC also indicated that the mixture was largely composed of N-ethylsaccharin. The more prevalent product structure is:
4. There are other types of reagents used to determine what type of biomolecule a substance is. For example, copper ions present in Benedict’s reagent reacts with the free end of any reducing sugars, such as glucose, when heated. Originally blue in color, these copper ions are reduced by the sugar, and produce an orange-red colored precipitate. Alternatively, iodine-potassium iodide (IKI) may also be used when working with starch. IKI contains special tri-iodine ions which interact with the coiled structure of a starch
All living things contain some form of organic macromolecules including: Lipids, proteins, carbohydrates and nucleic acids. All of these organic molecules are alike in the sense that is they are made up of bonded elements such as carbon, hydrogen, oxygen, and to smaller quantities nitrogen, phosphorus and sulfur. The macromolecules each contain large long chains of carbon and hydrogen atoms and often consists of repeating smaller molecules bonded together in a repeating pattern (polymers). To test whether a specific solid white substance is a protein is simple due to the unique chains found in the respective type of macromolecule. To test if the substance is a carbohydrate, two tests could be performed on separate samples of the object. First,
This experiment consisted of setting up a control group of starch in various temperature and then placing both fungal amylases and bacterial amylases in a mixture of starch and placing the solution of amylase and starch in various temperatures of water. After a certain amount of time- different amount of time needs to be used in order to have reliable results- iodine is added in a well on spot plates, then two drops of the mixture of amylase-starch is added from each temperature used, by adding iodine into the plates the mixture will show how much starch was hydrolyzed, this is used to calculate the amount of
In this lab experiment the action of the enzyme Amylase was observed on starch (the substrate). Amylase changed the starch into a simpler form, the sugar maltose, which is soluble in water. Maltose then breaks down the glucose chains of starch in the pancreas and intestines. Amylase is present in human saliva, and begins to act on the starch in the food while still in the mouth. Exposure to heat or extreme PH (acid or base) will denature proteins. Enzymes, including amylase, are proteins; if denatured enzymes can no longer act as a catalyst for the reaction. In the presence of potassium iodide, starch turns a dark purple color; however maltose does not react with I2KI. The rate of fading of starch allows a quantitative measurement of reaction rate.
Dispense .5 mL water into the already weighed conical vial, replace cap and face insert on its down side.
Atoms are the basic units of matter and all life is based on them. Life on earth is based on the element carbon. It is a highly versatile atom able to form four covalent bonds with itself or other atoms such as hydrogen and water. Atoms combine to form molecules and those that are carbon based are referred to as organic molecules. Organic molecules occur in four different types in living cells; carbohydrates, lipids, proteins and nucleic acids. They are also known as hydrocarbons due to the presence of both hydrogen and carbon. Carbohydrates are made up of carbon, hydrogen and oxygen in the ratio 1:2:1. They are important sources of energy and are classified in three main groups; monosaccharides, disaccharides and polysaccharides.
The first example of macroscopic change I observed is the color change from the combination of Starch + I2. The second example of macroscopic chemical change is the sediment formed by the combination of MgS04 and NH3. The third example is the foam from the mixture of Na2CO3+ CH3COOH
A cell, the building block of all living organisms, is composed of four fundamental biomolecules: proteins, carbohydrates, sugars and lipids. Proteins provide a vast amount of functions cells such as they serve as enzymes, provide structural support to cells, and act as antibodies. Reagents are used to spark a chemical reaction. The reagent used to detect protein traces in a substance is Biuret’s. Biuret’s will turn purple if proteins are present and blue if they are none. Biuret’s copper particles, have a charge of +2, are diminished to a charge of +1 when peptide bonds, which are in proteins, are present, creating the color change. Polysaccharides, which are carbohydrates, are most notably known to provide energy to the body, but they also help in breaking down fatty acids. Iodine is the reagent used to determine whether a substance has starch in it. The iodine/starch complex has energy levels that are only for retaining unmistakable light, giving the complex its extraordinarily dark black-blue shade. If there is no starch found, iodine will remain its natural yellowish-brownish color, but if starch is present, iodine will turn blue-black. Monosaccharides, which are sugars, like polysaccharides, provide the body with energy. To detect monosaccharides, the reagent, Benedict’s, is used. Benedict’s reagent is added to a test tube, then it is placed in
0.0375 mg/ml Porcine Pancreatic Amylase Solution (amylase powder in 0.9% NaCl ), Iodine Solution; each solution were pipetted into each of the 5 test tubes with 5 ml of 1% starch. Each tube contained a 1% starch solution with a different pH. All tubes were at room temperature. Room temperature was 22C. 0.2 ml of porcine pancreatic amylase solution was then pipetted into each tube. A timer was started and every 3minutes the starch / amylase mixture were pipetted from each tube and pipetted into the spot plate for every sample tube, then the iodine solution were added to a spot plate cell for each sample. Iodine reacts with starch to change from yellow to deep blue /black in the presence of starch. A lightening of the blue/ black to a brown color will occur as less starch is present. Results were reported as (+) for presence of starch in the sample or (–) for the absence of starch. After every three minute increment had passed, these same
Solutions and color reaction for Benedict’s test for reducing sugars and 2 iodine test for starch
Unknown biological molecules can be correctly identified using various tests, including colorimetric chemical tests. Colorimetric tests are when a chemical reagent, such as Benedict’s, is used on a substance or solution and a certain color change occurs as a response. Carbohydrates and proteins, two of the larger types of biological molecules, also called macromolecules, are actually chains of molecules called polymers. The smaller molecules that build up these chains are
The iodine test is used to identify glycogen and starch. These polysaccharides combine with iodine to