Test for the Presence of Macromolecules

Topics: Metabolism, Nutrition, Glucose Pages: 8 (1168 words) Published: November 14, 2013


Test for the Presence of Macromolecules

Introduction
In this experiment, we are trying to identify the presence of macromolecules in certain solutions. As in our daily lives, macromolecules are the essential nutrients that we have to take every day, therefore we would like to identify the types of macromolecules that contain in some of the food or solution in order to maintain a healthy life. There are four groups of macromolecules which are carbohydrates, lipids, proteins and nucleic acid. They are mostly made up of hydrogen, carbon, oxygen, nitrogen, sulphur and phosphorus. 1. Carbohydrates

Carbohydrates are organic compounds that with the combination of carbon, hydrogen and oxygen in a 1:2:1 ratio. Carbohydrates can be separated into three groups, monosaccharide, disaccharides and polysaccharides. Monosaccharide is the monomer of carbohydrates which contain hydroxyl group, such as glucose and fructose. Disaccharides are sugars that contain either aldehydes or ketone that react with hydroxyl group, such as maltose and lactose. Polysaccharides are the long chains of monosaccharide, which is called the polymer of carbohydrates. Monosaccharide and disaccharides can be tested by the Benedict’s test, as they are reducing sugars. Polysaccharides such as starch and glycogen can be tested by the iodine test. Also, carbohydrates are consumed to provide energy to our body and they are useful in metabolism. Therefore, it is one of the essential macromolecule that we have to consume. 2. Lipids

Lipids are made up of a glycerol molecule and three fatty acid molecules. They act as the energy source of human and they made up the phospholipid bilayer of the cell membrane. They can be simply divided into two groups, unsaturated and saturated fat. The only difference between saturated and unsaturated fat in structure is unsaturated fat has a double bond but saturated fat do not. Although some of the lipids can be made by biosynthetic pathway, some of the essential lipids need to be obtained by diets. 3. Proteins

Proteins are made up of a long chain of amino acids called polypeptide, they are formed with the peptide bond. Different proteins are composed with different sequences of amino acids, every protein are made with a specific sequence of amino acid. Proteins are functioned as the transportation between cells, provide support to the cell membrane and produce enzymes that catalyze chemical reactions in bodies. 4. Nucleic acids

Nucleic acids are made up of monomers called nucleotides, each nucleotide consist of a nitrogenous base, a phosphate group and a pentose sugar. They can be divided into two groups, DNA and RNA. The differences between DNA and RNA are DNA has one less oxygen than RNA, also, DNA has the nitrogenous bases of A, T, C and G when RNA has the base U instead of T. They are both important to the forms of life, as they are used in the replication within cell division and pass on the hereditary information. Testes for macromolecules

1. Iodine test
Iodine test is used to test on the presence of starch and glycogen, it is simply performed by adding few drops of iodine solution into the testing solution in the spot plate, then observe for the colour change, if the colour changes from yellow to blue-black, that’s mean the testing solution contains starch. If the colour changes from yellow to brown, that’s mean the testing solution contains glycogen. 2. Benedict’s test

Benedict’s test is used to test on the presence of reducing sugars, all of the monosaccharide and most of the disaccharides. It is simply performed by adding a certain amount of Benedict solution into the testing solution in the test tube, then put into the water bath for around 5 minutes and observe for colour changes. If the colour remain unchanged, which is blue in colour, that’s mean the testing solution does not contain reducing sugar. If the colour did change, ranged from green to brown, depends on how high the...
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