Biology Experiment Procedures PDF

1. Color Reactions of Proteins (Exercise No. 5) This experiment aims to detect the presence of specific amino acids and proteins through various colorimetric tests. Below is an outline of the key procedures and their expected results: Biuret Test: Procedure: Add NaOH and CuSO₄ to a sample. Positive...

1. Color Reactions of Proteins (Exercise No. 5) This experiment aims to detect the presence of specific amino acids and proteins through various colorimetric tests. Below is an outline of the key procedures and their expected results: Biuret Test: Procedure: Add NaOH and CuSO₄ to a sample. Positive Result: Violet color indicates the presence of peptide bonds. Ninhydrin Test: Procedure: Heat the sample with ninhydrin reagent. Positive Result: Purple color signifies the presence of amino acids or peptides. Xanthoproteic Test: Procedure: Add nitric acid, heat, then add NaOH. Positive Result: Yellow to orange color indicates aromatic amino acids like tyrosine. Pauly's Diazo Test: Procedure: Mix sulfanilic acid, sodium nitrite, and sodium carbonate with the sample. Positive Result: Red or orange color suggests histidine or tyrosine. Millon-Nasse Test: Procedure: Add Millon’s reagent and nitric acid. Positive Result: Red color indicates tyrosine. Hopkins-Cole Test: Procedure: Mix glyoxylic acid and sulfuric acid with the sample. Positive Result: Purple ring suggests tryptophan. Lead Sulphide Test: Procedure: Add NaOH, heat, then add lead acetate. Positive Result: Black precipitate indicates cysteine. Sakaguchi Test: Procedure: Add NaOH, alpha naphthol, and hypobromite. Positive Result: Red color indicates arginine. 2. Enzymatic Browning of Fruits and Vegetables (Exercise No. 6) This experiment investigates the browning of fruits and vegetables due to enzymatic activity. The primary enzyme involved is polyphenol oxidase (PPO). Procedure: Prepare six soaking solutions: ascorbic acid, syrup, salt, calamansi juice, plain water, and milk. Slice banana, potato, and apple samples, then soak them in each solution. Expose the slices to air for 45 minutes and observe changes. Results: The control slices usually show the highest degree of browning due to the exposure of polyphenols to oxygen. Soaking in ascorbic acid and syrup reduces browning by acting as antioxidants or reducing oxygen contact. Calamansi (acidic) and salt solutions slow the browning process by lowering pH or inhibiting enzyme activity. Milk may show variable results depending on its interaction with polyphenols. 3. Analysis of Bile Pigments and Bile Salts (Exercise No. 8) This experiment identifies the presence of bile pigments and bile salts in urine samples through specific tests. Smith’s Test (Bile Salts): Procedure: Mix Smith’s reagent with a urine sample. Positive Result: Green ring at the junction of layers indicates bile salts. Pettenkofer’s Test (Bile Salts): Procedure: Add sucrose and concentrated H₂SO₄ to the urine sample. Positive Result: Red color indicates bile salts. Hay’s Sulfur Powder Test (Bile Salts): Procedure: Add sulfur powder to water and urine samples. Positive Result: Sinking of sulfur powder in the urine sample indicates reduced surface tension by bile salts. Fouchet’s Test (Bile Pigments): Procedure: Treat the urine sample with barium chloride and Fouchet’s reagent. Positive Result: Green coloration indicates the presence of biliverdin, a bile pigment. Summary and Outline of the Activity: Extraction of DNA I. Introduction Key Concepts: DNA is a biopolymer storing genetic information. RNA plays a critical role in protein synthesis and gene expression. The process of DNA extraction involves three major steps: Lysis: Breaking open the cell to release DNA. Precipitation: Separating DNA from other cell components. Purification: Removing contaminants from the extracted DNA. II. Materials and Methodology Materials Biological samples (cheek swab, banana, another fruit of choice). Reagents: Salt, dishwashing soap, isopropyl alcohol, distilled water. Equipment: Beakers, graduated cylinder, funnel, filter paper, etc. Procedure 1. Cheek Swab Extraction: Gargle salty water, add soap, mix gently, and layer with alcohol. Observe DNA precipitation after 10 minutes. 2. Banana Extraction: Mash banana, mix with salt-soap solution, filter, and layer with alcohol. Scoop, dry, and preserve the DNA. 3. Other Fruit Extraction: Repeat the process from the banana procedure with a different fruit. IV. Questions for Research 1. Applications of DNA Extraction: Examples include genetic research, forensics, diagnostics, agriculture, and ancestry studies. 2. Lysis: The process of breaking open cells to release DNA. Essential for accessing the genetic material within the cell. 3. Salt Solution Purpose: Neutralizes DNA's negative charge to facilitate precipitation. 4. Isopropyl Alcohol Purpose: Causes DNA to precipitate as it is insoluble in alcohol. 5. Summarized Steps: Cell lysis → DNA precipitation → Purification. 6. Using Lettuce Instead of Banana: Lettuce can be used as a DNA source due to its cellular structure. 7. Drawings of Molecular Structures: Includes pentose sugars (ribose and deoxyribose), pyrimidines, and purines. This outline highlights the methodology, results, and research questions related to the activity. If you need additional details or help, let me know!