Proteins, Carbohydrates, and Fats/Oils: Structures, Tests, and Uses

Introduction to Biomolecules

Biomolecules like proteins, carbohydrates, and fats/oils are essential for life. They have unique structures and functions that are crucial for the body's metabolism and energy storage.

Proteins

Structure: Proteins are made up of amino acids linked by peptide bonds. They fold into specific shapes that determine their function.

Tests for Proteins:

• Biuret Test: Add Biuret reagent to a protein solution. A purple color indicates the presence of proteins.
• Ninhydrin Test: Ninhydrin reacts with amino acids to produce a purple color.
• Xanthoproteic Test: Add concentrated nitric acid to proteins. A yellow color indicates the presence of aromatic amino acids.
• Millon’s Test: Millon’s reagent reacts with phenolic groups in proteins to give a red color.

Uses: Proteins are vital for building and repairing tissues, making enzymes, hormones, and other body chemicals.

Carbohydrates

Structure: Carbohydrates are composed of carbon, hydrogen, and oxygen. They can be simple sugars (monosaccharides) or complex (polysaccharides).

Tests for Carbohydrates:

• Benedict’s Test: Add Benedict’s solution to a carbohydrate solution and heat. A brick-red precipitate indicates reducing sugars.
• Iodine Test for Starch: Iodine solution turns blue-black in the presence of starch.

Uses: Carbohydrates are the body's main energy source. They are also important for cell structure and communication.

Fats and Oils

Structure: Fats and oils are composed of glycerol and fatty acids. They are hydrophobic and store energy efficiently.

Tests for Fats and Oils: The presence of fats can be tested by the grease spot test or by using Sudan III stain, which colors fats red.

Uses: Fats and oils provide long-term energy storage, insulation, and protection for organs.