Biological Macromolecules Lab 1 Fall24 (1) (copy)

Introduction to Biological Macromolecules

• Big Idea: The structure and properties of molecules are important for their function in organisms.

• Learning Objectives:

  • Distinguish the unique properties of carbohydrates, lipids, proteins, and nucleic acids.

  • Understand how their chemical properties are important for function.

  • Explain the importance of positive and negative experimental controls.

  • Use biochemical tests to analyze an unknown.

Before Lab

• Review Chapter 3 from your textbook.

• Thoroughly read the laboratory module.

• Complete the pre-lab Canvas quiz.

• Print the lab module for the class session.

During Lab

• Complete data for Tables 1-5.

• Answer questions related to the experiments.

• Turn in exit questions before leaving.

After Lab

• Upload the post-lab assignment (Excel document) to Canvas.

• Take the post-lab Canvas Quiz.

Safety Precautions

• Be cautious with chemicals such as Benedict's, Biuret reagents, NaOH (highly corrosive), and others including:

  • Biuret can stain skin.

  • Dische diphenylamine and acetone are toxic.

  • Sudan IV stains clothing.

• Wear gloves and eye protection.

• Caution around boiling water bath.

Biological Macromolecules Overview

• The most abundant organic compounds in living organisms:

  • Carbohydrates

  • Proteins

  • Lipids

  • Nucleic Acids

• Each macromolecule is made of smaller precursor subunits.

• Dehydration Synthesis: Energy-requiring process where water is removed to bond subunits covalently.

• Hydrolysis: Energy-releasing process requiring the addition of water to break bonds.

• Enzymes are necessary for both processes.

Carbohydrates

• Composed of Carbon (C), Hydrogen (H), Oxygen (O) in a 1:2:1 ratio (e.g., C6H12O6 for glucose).

• Made of Monosaccharides (simple sugars):

  • Form Disaccharides (e.g., sucrose: glucose + fructose).

  • Form Polysaccharides (e.g., starch, glycogen, cellulose).

• Glycosidic Bonds form between hydroxyl groups through dehydration.

• Glucose as an energy source: stored as glycogen in animals and starch in plants.

• Cellulose: Structural component of plant cell walls and the most abundant organic molecule on Earth.

Proteins

• Composed of Amino Acids; each contains:

  • Amino group (-NH2)

  • Carboxyl group (-COOH)

  • Variable side chain (-R)

• Peptide Bonds form through dehydration between amino acids.

• Functions include:

  • Immunity (antibodies)

  • Transport (hemoglobin)

  • Hormonal (insulin)

  • Structural (keratin)

  • Metabolic (enzymes)

Lipids

• Diverse, nonpolar molecules that dissolve in nonpolar solvents (e.g., ether, acetone).

• Triglycerides: Composed of glycerol and three fatty acids through ester bonds.

• Phospholipids: Similar to triglycerides, but with a phosphate group instead of one fatty acid.

• Steroids: Include cholesterol; have four fused carbon rings with different functional groups.

• Functions:

  • Long-term energy storage.

  • Key components of cell membranes (phospholipids).

  • Hormonal signaling (steroids).

• Lipids are not true polymers; require multiple subunits.

Nucleic Acids

• DNA and RNA: Composed of nucleotide subunits.

• Phosphodiester Bonds form between sugar and phosphate groups in nucleotides.

• Differences:

  • DNA: Contains deoxyribose sugar, nitrogenous bases A, G, C, T.

  • RNA: Contains ribose sugar, nitrogenous bases A, G, C, U.

• DNA forms a double helix; RNA is single-stranded.

• Major Role of DNA: Contains genetic instructions for protein production, transmitted via RNA.

• RNA translates genetic code, relaying information from DNA to ribosomes for protein assembly.

Controlled Experiments

• Chemical tests to detect cellular organic molecules involve:

  • Unknown solution to identify.

  • Control solutions to validate results.

• Positive Control: Contains the variable being tested (e.g., known protein solution).

• Negative Control: Does not contain the variable (e.g., distilled water).

Testing Procedures

1. Benedict's Test for reducing sugars (detects glucose and fructose).

   • Color change indicates presence; blue indicates no reducing sugars.

2. Iodine Test for starch (coiled sugars turn bluish-black; others remain yellow-brown).

3. Dische Diphenylamine Test for DNA (blue complex formation indicates presence).

4. Biuret Test for proteins (violet color indicates peptide bonds).

5. Lipids Test based on solubility in polar vs nonpolar solvents and using Sudan IV.

Identification of an Unknown

• Tests help identify components of unknown solutions using previous tests for reliability and specificity.

Open Inquiry

• Suggestions for future experiments:

  • Testing for additional organic substances.

  • Examining treatments that could affect detection of macromolecules.