Ninhydrin and Biuret Tests for Amino Acids and Proteins
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Questions and Answers

What is the main functional group responsible for the reduction of metal ions in reducing sugars?

  • Hemiacetal
  • Enediol (correct)
  • Keto
  • Aldehyde

    • Which test is used to differentiate between reducing and non-reducing sugars?

  • Tollen's Silver Mirror Test
  • Fehling's Test
  • Benedict's Test (correct)
  • All of the above

    • What is the characteristic structure of an osazone when viewed under a microscope?

  • Fibrous
  • Amorphous
  • Crystalline (correct)
  • Gelatinous

    • What is the result of the reaction between a reducing sugar and copper (II) ions in Benedict's Test?

    <p>Reduction of copper (II) ions to copper (I) ions</p> Signup and view all the answers

    Which of the following sugars does not have a free carbonyl group?

    <p>Cellulose</p> Signup and view all the answers

    What is the anionic form of enediol that carries a negative charge?

    <p>Enediolate</p> Signup and view all the answers

    Which of the following sugars is a non-reducing sugar?

    <p>Sucrose</p> Signup and view all the answers

    What is the primary component of starch in plants?

    <p>Glucose</p> Signup and view all the answers

    Which test is specific for fructose in the presence of glucose?

    <p>Indole-3-acetic acid test</p> Signup and view all the answers

    What is the purpose of Fehling's Test?

    <p>To differentiate between reducing and non-reducing sugars</p> Signup and view all the answers

    Which of the following sugars is not a reducing sugar?

    <p>Sucrose</p> Signup and view all the answers

    What is the temperature range required for the indole-3-acetic acid test?

    <p>40-50°C</p> Signup and view all the answers

    What is the primary purpose of the Biuret test?

    <p>To detect the presence of amino acids or proteins</p> Signup and view all the answers

    What is the positive indication of the Sakaguchi's test?

    <p>Red color</p> Signup and view all the answers

    Which test is used to detect the presence of aromatic amino acids?

    <p>Ehlrich's test</p> Signup and view all the answers

    What is the result of the Xanthoproteic test on casein?

    <p>Positive</p> Signup and view all the answers

    What is the effect of heat on proteins?

    <p>Denaturation</p> Signup and view all the answers

    Which reagents are used in the Hopkins-Cole reaction?

    <p>Lead acetate and glyoxylic acid</p> Signup and view all the answers

    What is the result of the Ninhydrin test on arginine?

    <p>Positive</p> Signup and view all the answers

    What is the result of the Lead Acetate test on cysteine?

    <p>Black precipitate</p> Signup and view all the answers

    What is the result of the Nitroprusside reaction on cysteine?

    <p>Positive</p> Signup and view all the answers

    Which test is used to detect the presence of peptides/proteins?

    <p>Pauly's test</p> Signup and view all the answers

    Which of the following tests is used to differentiate aldoses and ketoses?

    <p>Seliwanoff test</p> Signup and view all the answers

    What is the purpose of the Molisch test?

    <p>To detect the presence of carbohydrates</p> Signup and view all the answers

    What is the color produced by the Molisch test in the presence of carbohydrates?

    <p>Purple or red-violet</p> Signup and view all the answers

    What is the purpose of the Anthrone test?

    <p>To detect the presence of carbohydrates</p> Signup and view all the answers

    Which of the following compounds produces a cherry red color in the Seliwanoff test?

    <p>Fructose</p> Signup and view all the answers

    What is the purpose of Bial's test?

    <p>To differentiate pentoses and hexoses</p> Signup and view all the answers

    What is the result of the Molisch test with starch?

    <p>Negative, no color change</p> Signup and view all the answers

    What is the result of the Anthrone test with glucose?

    <p>Positive, purple-red color</p> Signup and view all the answers

    What is the purpose of the Tollen's phloroglucinol test?

    <p>To detect the presence of pentoses and other compounds that can yield furfural derivatives</p> Signup and view all the answers

    What is the result of the Seliwanoff test with arabinose?

    <p>Positive, green color</p> Signup and view all the answers

    What is the primary purpose of the Mucic Acid Test?

    <p>To detect the presence of galactose</p> Signup and view all the answers

    What is the characteristic of soap that allows it to act as a surfactant?

    <p>Its hydrophilic and hydrophobic contents</p> Signup and view all the answers

    What is the purpose of the Rosenheim's Test for Choline?

    <p>To detect the presence of choline, phospholipids, cerebrosides, and sphingomyelins</p> Signup and view all the answers

    What is the result of the Saponification reaction?

    <p>The formation of soap and glycerol</p> Signup and view all the answers

    What is the purpose of the Solubility Test?

    <p>To determine the solubility of fats and oils</p> Signup and view all the answers

    What is the characteristic of an insoluble soap?

    <p>It is water insoluble and oil soluble</p> Signup and view all the answers

    What is the purpose of the Lieberman-Burchard Test?

    <p>To detect the presence of cholesterol</p> Signup and view all the answers

    What is the result of the Salting Out reaction?

    <p>The formation of a precipitate</p> Signup and view all the answers

    What is the purpose of the Iodine Test?

    <p>To distinguish between saturated and unsaturated fatty acids</p> Signup and view all the answers

    What is the characteristic of a sample that yields a positive result in the Mucic Acid Test?

    <p>It contains galactose</p> Signup and view all the answers

    Study Notes

    Reducing Sugars

    • The aldehyde group is responsible for the reduction of metal ions in reducing sugars.
    • Benedict's Test is used to differentiate between reducing and non-reducing sugars.
    • A positive Benedict's Test results in the formation of a red precipitate of copper(I) oxide.

    Osazones

    • Osazones are crystalline derivatives of sugars formed by reaction with phenylhydrazine.
    • Under a microscope, osazones have a characteristic needle-like or feather-like structure.

    Sugars

    • Sucrose does not have a free carbonyl group.
    • Enediol is an intermediate in the process of isomerization of sugars.
    • Sucrose is a non-reducing sugar.
    • Amylose is the primary component of starch in plants.

    Fructose and Glucose Tests

    • Seliwanoff's Test is specific for fructose in the presence of glucose.
    • Fehling's Test is used to detect the presence of reducing sugars.

    Protein Tests

    • Biuret Test is used to test for the presence of peptide bonds in proteins.
    • Biuret Test gives a positive result with a violet color.
    • Sakaguchi's Test is used to detect the presence of arginine.
    • A positive Sakaguchi's Test results in a red color.
    • Xanthoproteic Test is used to detect the presence of aromatic amino acids.
    • A positive Xanthoproteic Test results in a yellow color.
    • Casein gives a positive result in the Xanthoproteic test.
    • Ninhydrin Test is used to detect the presence of amino acids.
    • A positive Ninhydrin Test results in a purple color.
    • Arginine gives a positive result in the Ninhydrin test.
    • Hopkins-Cole Test is used to detect the presence of tryptophan.
    • Lead Acetate Test is used to detect the presence of cysteine.
    • A positive Lead Acetate Test results in a black precipitate.
    • Nitroprusside Test is used to detect the presence of cysteine.
    • A positive Nitroprusside Test results in a red color.

    Carbohydrate Tests

    • Molisch Test is used to detect the presence of carbohydrates.
    • A positive Molisch Test results in a purple color.
    • Anthrone Test is used to detect the presence of carbohydrates.
    • A positive Anthrone Test results in a blue-green color. Fructose produces a cherry red color in the Seliwanoff Test.
    • Bial's Test is used to detect the presence of pentoses.
    • Starch gives a positive result in the Molisch test.
    • Glucose gives a positive result in the Anthrone test.
    • Tollen's phloroglucinol test is used to detect the presence of pentoses.
    • Arabinose gives a negative result in the Seliwanoff test.
    • Mucic Acid Test is used to detect the presence of galactose.

    Soap Tests

    • Mucic Acid Test yields a positive result with a white precipitate.

    Lipid Tests

    • Rosenheim's Test is used to detect the presence of choline.
    • Saponification reaction is used to hydrolyze fats and oils into fatty acids and glycerol.
    • Solubility Test is used to determine the solubility of a substance in a particular solvent.
    • Insoluble soaps are typically made from fatty acids with a long chain.
    • Lieberman-Burchard Test is used to detect the presence of cholesterol.
    • Salting Out is a process used to separate proteins from solution.
    • Iodine Test is used to detect the presence of starch.

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    Description

    This quiz covers the principles and results of Ninhydrin and Biuret tests, which are used to detect the presence of amino acids and proteins. Learn about the ingredients, indications, and results of these tests. Practice identifying the tests' positive and negative results.

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