Lab practical study guide.pdf

Bio 101 Lab Practical Study Guide Name Safety Items Lab Coat: Protects clothing and skin from spills. Goggles: Protects eyes from splashes of chemicals or broken glass. Gloves: Protects hands from harmful substances. Fume Hood: Used for working with volatile chemicals to co...

Bio 101 Lab Practical Study Guide Name Safety Items Lab Coat: Protects clothing and skin from spills. Goggles: Protects eyes from splashes of chemicals or broken glass. Gloves: Protects hands from harmful substances. Fume Hood: Used for working with volatile chemicals to contain fumes. Fire Extinguisher: For emergency situations involving fire. Emergency Shower and Eyewash Station: Used for chemical spills on the body or in the eyes. First Aid Kit: Contains medical supplies for minor injuries. 2. How to Measure in mL, g, etc. Milliliters (mL): Used for measuring liquid volumes. Commonly done with graduated cylinders, pipettes, or beakers. Grams (g): Used for measuring mass, typically using an electronic balance or scale. Microliters (μL): For very small volumes, often used in micropipettes. Precision: Ensure accuracy by using the correct measuring device for the quantity being measured. 3. Lab Hardware Test Tubes: Small cylindrical glass containers used to hold or mix substances. Test Tube Holder: Used to hold test tubes, especially when hot or during experiments. Forceps: Tweezers-like tools for grasping small objects. Beakers: Used for holding, mixing, or heating liquids. Graduated Cylinders: Measure liquid volumes with greater accuracy than beakers. Pipettes: Used to measure and transfer small amounts of liquids. 4. DI Water (Deionized Water) Definition: Water that has been purified by removing ions (salts, minerals). Uses: Prevents contamination in experiments, used as a solvent in solutions. 5. Independent vs. Dependent Variables Independent Variable: The variable that is changed or controlled in an experiment to test its effects.  ○ Example: The type of fertilizer applied to plants. Dependent Variable: The variable that is observed or measured in response to changes in the independent variable. ○ Example: The growth of the plant in response to the fertilizer. Identification: ○ Independent: What the experimenter changes. ○ Dependent: What is measured or observed. 6. Solutions Used to Test Proteins, Carbohydrates, etc. Biuret Test: Tests for proteins. Turns purple in the presence of proteins. Benedict’s Solution: Tests for reducing sugars (carbohydrates). Turns from blue to red/orange when heated if sugar is present. Iodine Test: Tests for starch. Turns blue-black in the presence of starch. Sudan IV: Tests for lipids. Turns red or orange in the presence of lipids. 7. Toothpick Method with Powder What It’s Testing For: Identifies whether a sample contains starch. How It Works: A toothpick dipped in iodine solution is used to test for starch in a powder. If starch is present, the iodine changes color to a blue-black. 8. Electrolyte Tester and How to Read It Electrolytes: Substances that conduct electricity when dissolved in water (e.g., salts, acids, bases). Tester Use: Measures the conductivity of a solution. Reading the Tester: A high conductivity reading means the solution has many electrolytes; a low reading indicates few or none. 9. Compound Microscope How to Use It:  1. Stage: Place the specimen slide here with the slide clips holding it. 2. Light Source: Illuminate the specimen. 3. Objective Lenses: Different magnifications (e.g., 4x, 10x, 40x). 4. Ocular Lenses: Where you look through, typically 10x magnification. 5. Coarse/Fine Adjustment Knobs: Focus the image. 6. What It’s Used For: Viewing small organisms or structures (e.g., cells, tissues). 7. Total Magnification: Multiply the ocular lens magnification (usually 10x) by the objective lens magnification (e.g., 40x objective x 10x ocular = 400x magnification). 10. Total Magnification Calculation Formula: Total Magnification = Objective Lens Magnification x Ocular Lens Magnification Example: 10x ocular lens with a 40x objective lens = 400x total magnification. 11. Positively and Negatively Charged Atoms Positively Charged Atoms (Cations): Atoms that have lost one or more electrons. Negatively Charged Atoms (Anions): Atoms that have gained one or more electrons. Example: Sodium ion (Na+) is a cation; Chloride ion (Cl-) is an anion. 12. Onion Root Tip Purpose: Used to observe stages of cell division (mitosis). Preparation: Root tips are stained and viewed under a microscope to identify phases such as interphase, prophase, metaphase, anaphase, and telophase. 13. Identify Macromolecules Proteins: Made of amino acids. Tested using Biuret solution (turns purple). Carbohydrates: Includes sugars (monosaccharides) and starches (polysaccharides). Tested with Benedict’s (for sugars) and Iodine (for starches). Lipids: Fats and oils, tested with Sudan IV (turns red). Nucleic Acids: DNA and RNA, not typically tested in basic labs but identified by their molecular components. Label the Parts of a Light Compound Microscope Below is a guide for labeling the parts of a light compound microscope. Use this to label the diagram correctly: Eyepieces (Ocular): Where you place your eyes to look through the microscope, usually with 10x magnification. Arm: Supports the microscope and is used to carry it. Revolving Nosepiece: Holds the objective lenses and allows you to rotate between different magnifications. Objectives: The lenses closest to the specimen that magnify the image (commonly 4x, 10x, 40x, and 100x). Stage: The platform where the slide is placed for viewing. Condenser: Focuses the light onto the specimen. Iris Diaphragm: Controls the amount of light passing through the specimen. Light Source: Provides light to illuminate the specimen. Base: The bottom of the microscope, provides stability. Coarse Adjustment Knob: Used to bring the specimen into general focus by moving the stage up and down. Fine Adjustment Knob: Fine-tunes the focus of the specimen. Stage Clip: Holds the slide in place on the stage. As you increase magnification, you decrease the working distance As you increase magnification, you decrease the field of view As you increase magnification, you increase the depth of field As you increase magnification, you decrease the illumination intensity Cell Types a) Prokaryotic Organism Type of Cell: Prokaryotic- looks like a giant eyeball b) Protista Type of Cell: Protista- usually long and skinny c) Plant Cell Type of Cell: Plant- looks like bricks d) Animal Cell Type of Cell: Animal- looks like mini water balloons  Testing for Macromolecules Macromolecules, such as carbohydrates, proteins, lipids, and nucleic acids, are essential components of living organisms. Each type of macromolecule can be detected using specific biochemical tests. Below is a detailed explanation of how to test for each type of macromolecule: 1. Carbohydrates Carbohydrates can be divided into two types: -simple sugars (monosaccharides and disaccharides) -complex sugars (polysaccharides, like starch). a) Benedict’s Test for Reducing Sugars (Monosaccharides & Some Disaccharides)- think egg. Needs to be heated up Purpose: Detects reducing sugars (e.g., glucose, fructose). Reagent: Benedict’s solution (blue in color). Procedure: 1. Add 2 mL of Benedict’s solution to a test tube containing the sample 1ml. 2. Heat the solution in a water bath for 2-5 minutes. 3. Observe the color change. Positive Result: Color change from blue to green, yellow, orange, or red, indicating the presence of reducing sugars.  Explanation: Reducing sugars donate electrons to the copper(II) sulfate in Benedict’s solution, which causes the color change. b) Iodine Test for Starch (Polysaccharides) Purpose: Detects the presence of starch (a polysaccharide). Reagent: Iodine solution (yellow-brown in color). Procedure: 1. Add a few drops of iodine solution to the sample in a test tube. 2. Observe any color changes. Positive Result: The solution turns blue-black, indicating the presence of starch. Explanation: Iodine fits into the helical structure of starch, forming a blue-black complex. 2. Proteins Proteins are made up of amino acids linked by peptide bonds. The most common test for proteins is the Biuret test. Biuret Test for Proteins Purpose: Detects peptide bonds, which are indicative of proteins. Reagent: Biuret reagent (blue in color, contains copper(II) sulfate). Procedure: 1. Add 2 mL of Biuret reagent to the sample in a test tube. 2. Gently mix the solution. 3. Observe the color change. Positive Result: Color change from blue to purple or violet, indicating the presence of proteins. Explanation: The copper ions in the Biuret reagent react with the peptide bonds in proteins, producing a purple color. 3. Lipids Lipids are hydrophobic molecules such as fats and oils. The Sudan IV test is commonly used to test for lipids. Sudan IV Test for Lipids Purpose: Detects the presence of lipids. Reagent: Sudan IV (a red, non-polar dye). Procedure: 1. Add a few drops of Sudan IV to the sample in a test tube. 2. Shake the test tube to mix the solution. 3. Allow the solution to settle and observe the separation of layers. Positive Result: A red-stained oil layer separates out, indicating the presence of lipids. Explanation: Sudan IV is a fat-soluble dye that binds to lipids, making them visible as a red-stained layer. Sudan IV Tests Alternative Lipid Test: Grease Spot Test Procedure: 1. Rub the sample on a piece of brown paper or filter paper. 2. Allow the paper to dry. 3. Observe if a translucent spot remains. Positive Result: A translucent spot indicates the presence of lipids (since fats leave a greasy stain). 4. Nucleic Acids (DNA & RNA) While nucleic acids are not commonly tested in basic laboratory settings, specific tests such as the Dische diphenylamine test can be used to detect DNA. Dische Diphenylamine Test for DNA Purpose: Detects the presence of deoxyribose sugars in DNA. Reagent: Diphenylamine reagent. Procedure: 1. Add diphenylamine reagent to the sample. 2. Heat the mixture in a water bath. 3. Observe any color changes. Positive Result: A blue color indicates the presence of DNA. Explanation: The deoxyribose sugar in DNA reacts with the diphenylamine under acidic conditions, producing a blue color. Summary Table for Macromolecule Tests Macromolecule Test Name Reagent Positive Result Reducing Benedict’s Test Benedict’s solution Green(traces) → Yellow(moderate) Sugars- think of → Orange (moderate)→ Red(large a benedict egg amount of reducing sugars) Starch- think Iodine Test Iodine solution Blue-black color yellow potato Proteins Biuret Test Biuret reagent Purple/violet color Lipids-think Sudan IV Test Sudan IV Red-stained layer nasty fat ring around a soup bowl Lipids Grease Spot Brown paper Translucent spot Test DNA Dische Test Diphenylamine Blue color By following these procedures and using the appropriate reagents, you can successfully identify the presence of different macromolecules in biological samples.