Experiment 3: Macromolecules and Living Things PDF

EXPERIMENT 3 Macromolecules and Living Things GENERAL BIOLOGY LABORATORY INTRODUCTION Macromolecules are large, complex molecules with high molecular weights, typically consisting of thousands or millions of atoms. They play crucial roles in biological systems, as well as in...

EXPERIMENT 3 Macromolecules and Living Things GENERAL BIOLOGY LABORATORY INTRODUCTION Macromolecules are large, complex molecules with high molecular weights, typically consisting of thousands or millions of atoms. They play crucial roles in biological systems, as well as in synthetic materials. The primary types of macromolecules in biological systems: 1. Carbohydrates 2.Proteins 3.Nucleic acids  DEHYDRATION In dehydration reactions, a water molecule is formed as a result of generating a covalent bond between two monomeric components in a larger polymer: 1. Speed up by specific enzymes 2. Formation of bonds 3.Requiring energy  HYDROLYSIS Hydrolysis reactions result in the breakdown of polymers into monomers, this reaction: 1. Speed up by specific enzymes 2. Break chemical bonds 3.Release energy CARBOHYDRATE Functions in energy storage (starch and glycogen) and structural support and protection (cellulose and chitin). Organic compounds that contains Carbon (C), Hydrogen (H), Oxygen (O). Carbohydrates represented by the formula (CH2O)n, where n is the number of carbon atoms in the molecule. In other words, the ratio of C:H:O is 1:2:1 in carbohydrate molecules. CLASSIFICATION OF CARBOHYDRAYES MONOSACCHARIDES Monosaccharides are the simplest form of carbohydrates and are often referred to as simple sugars. They are the basic building blocks of more complex carbohydrates like disaccharides and polysaccharides. Monosaccharides consist of a single sugar unit and typically follow the chemical formula (CH2O)n, where n is the number of carbon atoms in the molecule. They are classified based on the number of carbon atoms and the functional groups they contain. Classification of Monosaccharides 1. Based on Carbon Atoms: Trioses: 3-carbon sugars (e.g., glyceraldehyde) Pentoses: 5-carbon sugars (e.g., ribose, found in RNA) Hexoses: 6-carbon sugars (e.g., glucose, fructose, galactose) 2. Based on the Functional Group: Aldoses: Contain an aldehyde group (-CHO) at the end of the molecule. Examples include glucose and ribose. Ketoses: Contain a ketone group (C=O) usually at the second carbon atom. Fructose is a well-known ketose. Classification of Monosaccharides DISACCHARIDES Disaccharides are carbohydrates composed of two monosaccharide units linked together by a glycosidic bond. When two monosaccharides undergo a dehydration reaction, a disaccharide is formed, along with the release of a water molecule. POLYSACCHARIDES Polysaccharides are complex carbohydrates composed of long chains of monosaccharide units linked together by glycosidic bonds. 1. Storage Polysaccharides: These polysaccharides serve as energy reserves in plants and animals. Starch: The main energy storage polysaccharide in plants. It consists of two components, Amylose and Amylopectin. Glycogen: The storage polysaccharide in animals, found in the liver and muscle tissues 2. Structural Polysaccharides: These provide structural support in cells and tissues. Cellulose: The primary structural component of plant cell walls. Chitin: Found in the exoskeletons of arthropods and the cell walls of fungi. BENEDICT’S TEST Benedict’s test is a fundamental chemical test used to identify the presence of reducing sugars in biological samples. Reducing sugars are sugars that have a free aldehyde or ketone group, allowing them to act as reducing agents. These groups can donate electrons, leading to the reduction of other substances. BENEDICT’S TEST All monosaccharides are reducing sugars because all of them have an open- chain form with a free aldehyde or ketone group that tautomerizes in solution to form an aldehyde group. e.g. Glucose, Galactose, Fructose, Ribose, and Xylose. Disaccharides are some reducing sugars and others are non-reducing sugars. Reducing sugars: Lactose and Maltose Non-Reducing sugars: Sucrose and Trehalose Some Polysaccharides are reducing sugar, others are Non BENEDICT’S REAGENT Benedict's reagent, often referred to as Benedict's solution, is a chemical reagent used to detect the presence of reducing sugars in a sample. It contains copper (II) sulfate (CuSO4), sodium carbonate (Na2CO3), and sodium citrate (Na3C6H5O7). The reagent is typically in an alkaline solution, which is achieved by adding sodium carbonate to make it slightly basic with a pH ranging from 9 to 10. The Principle Behind Benedict’s Test In the alkaline environment provided by sodium carbonate, the copper (II) ions (Cu+2) in Benedict's reagent can be reduced to copper (I) ions (Cu+) by the aldehyde or ketone groups present in reducing sugars. This reduction reaction involves the transfer of electrons from the reducing sugar to the copper ions. Thereafter, the copper (I) ions (Cu+) produced during the reduction react further to form copper (I) oxide (Cu2O), which is insoluble in water and precipitates out of the solution The Principle Behind Benedict’s Test The Principle Behind Benedict’s Test The formation of copper(I) oxide results in a visible color change in the solution. Initially, the reagent is blue due to the presence of copper (II) ions. After the reaction with reducing sugars, the solution may turn green, yellow, orange, or red, depending on the concentration of reducing sugars present. A more intense color indicates a higher concentration of reducing sugars The Principle Behind Benedict’s Test The practical part of Benedict’s test Lugol’s test Lugol's test involves the use of Lugol's iodine solution, a brown-colored liquid made by dissolving iodine and potassium iodide in water. The resulting solution is primarily used as an indicator of the presence of starch. The iodine in Lugol's solution interacts with the starch molecules, resulting in a characteristic color change, which is the basis of the test. When Lugol's solution is added to a sample containing starch or polysaccharides, a chemical reaction occurs. The iodine in the solution interacts with the glucose units present in the starch, forming a complex known as a starch-iodine complex. This complex manifests as a deep blue-black color, indicating the presence of starch. Lugol’s Test Results Lugol’s Test Procedure Proteins Proteins are large, complex macromolecules composed of amino acids arranged in a specific sequence. They are essential for virtually every function in living organisms, including structure, catalysis of biochemical reactions, transport, defense, and regulation of cellular processes. Proteins are made of one or more polypeptide chains, which fold into a specific three-dimensional shape that determines their function. Amino Acids: The Building Blocks of Proteins Biuret Test The Biuret test is a widely used chemical assay to detect the presence of proteins in a given sample. The Biuret test relies on the reaction of peptide bonds, found in proteins, with copper ions (Cu²⁺) in an alkaline medium. Biuret (a copper sulfate solution in sodium hydroxide) can form a complex with copper ions in the presence of proteins. The copper ions coordinate with the nitrogen atoms in the peptide bonds, resulting in a violet to purple color change, indicating the presence of proteins Biuret Test Results Biuret Test Procedure Vitamin C (Ascorbic Acid) Vitamin C (Ascorbic Acid) is a water-soluble vitamin and a powerful antioxidant that plays numerous vital roles in the body. It is essential for the growth, development, and repair of body tissues, and because humans cannot synthesize it, it must be obtained through the diet. Vitamin C is found in many fruits and vegetables, especially citrus fruits, and is crucial for maintaining good health. Test of Vitamin C in different juices Testing the Vitamin C content in different juices can be an interesting experiment, and there are a few common methods to do this. One of the most straightforward ways is to use a titration method with an Indophenol solution, which reacts with Vitamin C (ascorbic acid). Indophenol is blue if the (pH >4), and colorless if the (pH