biomolecule Identification

POBS Lab 2 - Biomolecule Identification

Overview of Biomolecules

  • Definition: Biomolecules are organic molecules that constitute living organisms.

  • Types: The primary categories of biomolecules include carbohydrates, fats, proteins, and nucleic acids.

  • Lab Objective: In this lab, tests will be conducted to identify carbohydrates, fats, and proteins.

Carbohydrates

  • Description: Carbohydrates are organic molecules that primarily consist of carbon and water.

  • General Chemical Formula: The general formula for carbohydrates is given as C<em>n(H</em>2O)nC<em>n(H</em>2O)_n which indicates that for every carbon atom, there is a corresponding water molecule.

  • Types of Carbohydrates:

    • Monomers: The simplest form, known as monosaccharides, or simple sugars.

    • Polymers: Larger structures formed by linking multiple monomers.

  • Examples of Monosaccharides: Fructose, glucose, and galactose.

Molecular Structures of Common Monosaccharides

  • Fructose:

    • Structure: C₆H₁₂O₆ with arrangements showing hydroxyl and carbonyl groups.

  • Glucose:

    • Structure: C₆H₁₂O₆, with different stereochemistry than fructose.

  • Galactose:

    • Structure: Similar to glucose but differing in the configuration of the hydroxyl group.

Test for Monosaccharides: The Benedict's Test

  • Benedict's Reagent: A clear blue solution due to copper (II) ions.

  • Chemical Reaction: Monosaccharides react during heating, causing color changes indicating varying sugar concentrations.

    • Color Change Indicators:

    • Green: Indicates a small amount of sugar (0.1% to 0.5%).

    • Yellow/Orange: Indicates a moderate amount of sugar (0.5% to 1.0%).

    • Brick-Red: Indicates a high amount of sugar (>1.0%).

Procedure for Benedict's Test

  1. Preparation:

    • Use five clean test tubes numbered #1 to #5.

  2. Adding Solutions:

    • Tube #1: Add 1 ml of water.

    • Tube #2: Add 1 ml of 0.2% glucose solution.

    • Tube #3: Add 1 ml of 0.8% glucose solution.

    • Tube #4: Add 1 ml of 2.0% glucose solution.

    • Tube #5: Add 1 ml of the unknown solution.

  3. Reaction:

    • Add 5 drops of Benedict's reagent to each tube.

    • Place in boiling water bath for 5 minutes.

  4. Observation:

    • A color change indicates the presence of monosaccharide sugars.

  5. Record results in the notebook.

Starch

  • Definition: Starch is a polysaccharide made up of many glucose units, often comprising millions of glucose residues.

  • Function: It serves as the primary energy storage molecule in plants and is a crucial energy source for animals when broken down into glucose.

  • Storage: Excess glucose can be stored as glycogen in muscles and the liver.

  • Note on Solubility: Animals cannot store starch as it is insoluble, unlike plants.

Starch Detection: Lugol’s Iodine Test

  • Purpose: To detect the presence of starch in a sample.

  • Chemical Mechanism: Iodine interacts with starch molecules, turning them black upon binding and accommodating within the sugar residues.

Procedure for Lugol's Iodine Test

  1. Preparation:

    • Use three clean test tubes labeled #1 to #3.

  2. Adding Solutions:

    • Tube #1: Add 1 ml of water.

    • Tube #2: Add 1 ml of 0.01% starch solution.

    • Tube #