أسئلة المحاضرة الثانية بيو (قبل التعديل)
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Questions and Answers

What type of acid is D-glucaric acid classified as?

  • Hydroxyl acid
  • Polycarboxylic acid
  • Monocarboxylic acid
  • Aldaric acid (correct)

    • How many carbon atoms are in D-glucaric acid?

  • 8
  • 5
  • 7
  • 6 (correct)

    • Which of the following characteristics does D-glucaric acid possess?

  • It is a five-carbon acid.
  • It is insoluble in water.
  • It contains both carbonyl and hydroxyl groups. (correct)
  • It is optically inactive.

    • From which sugar is D-glucaric acid derived?

    <p>D-glucose (B)</p> Signup and view all the answers

    What property of D-glucaric acid contributes to its optical activity?

    <p>Presence of asymmetric carbon atoms (B)</p> Signup and view all the answers

    What is the primary consequence of low levels of lactase enzyme?

    <p>Undigested lactose (C)</p> Signup and view all the answers

    What process occurs to lactose that fails to be digested due to lactase deficiency?

    <p>Bacterial fermentation in the colon (D)</p> Signup and view all the answers

    What byproducts are generated as a result of lactose fermentation in the colon?

    <p>CO2, H2, and irritating organic acids (C)</p> Signup and view all the answers

    What typically results from low levels of lactase in the digestive system?

    <p>Bacterial fermentation of undigested lactose (B)</p> Signup and view all the answers

    Which of the following is not a result of undigested lactose in the colon?

    <p>Increased levels of lactase (B)</p> Signup and view all the answers

    What gases are primarily produced due to bacterial fermentation of lactose in individuals with low lactase levels?

    <p>Carbon dioxide and hydrogen (A)</p> Signup and view all the answers

    What leads to the generation of large amounts of CO2 and H2 in the digestive system?

    <p>Bacterial fermentation of undigested lactose (B)</p> Signup and view all the answers

    Which of the following symptoms is commonly associated with lactose intolerance?

    <p>Abdominal cramps (A)</p> Signup and view all the answers

    What is a consequence of the irritating organic acids generated from lactose fermentation in the colon?

    <p>Diarrhea (A)</p> Signup and view all the answers

    Which best describes the process occurring in the colon due to undigested lactose in individuals with low lactase levels?

    <p>Fermentation by bacteria (B)</p> Signup and view all the answers

    Which type of glycosidic bond connects two α-glucose molecules?

    <p>α 1-4 glycosidic (D)</p> Signup and view all the answers

    Which of the following is classified as a reducing sugar?

    <p>α-glucose (B)</p> Signup and view all the answers

    What is the process used to break down starch in the body?

    <p>Hydrolysis by Amylase (A)</p> Signup and view all the answers

    Which type of glycosidic bond is found in cellulose?

    <p>β 1-4 glycosidic (D)</p> Signup and view all the answers

    Which statement concerning dextran is correct?

    <p>Dextran contains both α 1-6 and α 1-4 glycosidic bonds. (A)</p> Signup and view all the answers

    What defines a painful digestive upset?

    <p>Painful digestive upsets (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic commonly associated with disaccharides?

    <p>They directly cause lactose intolerance. (C)</p> Signup and view all the answers

    Which of the following statements about sugar derivatives is accurate?

    <p>They participate in various biochemical reactions. (B)</p> Signup and view all the answers

    Which of the following contains both a disaccharide and a sugar derivative?

    <p>Cellulose and sucrose (A)</p> Signup and view all the answers

    What is a common result of the improper digestion of certain disaccharides?

    <p>Painful digestive upsets (D)</p> Signup and view all the answers

    What change occurs to the last hydroxyl carbon of D-glucuronic acid?

    <p>It is converted to a carboxylic group. (B)</p> Signup and view all the answers

    D-glucuronic acid is derived from glucose through which biochemical process?

    <p>Oxidation by glucose oxidase enzyme. (C)</p> Signup and view all the answers

    Which functional group is present in D-glucuronic acid as a result of the last carbon's transformation?

    <p>Carboxylic group. (B)</p> Signup and view all the answers

    Which of the following accurately describes the role of glucose oxidase in the formation of D-glucuronic acid?

    <p>It facilitates the oxidation of glucose, creating an acid form. (D)</p> Signup and view all the answers

    What distinguishes D-glucuronic acid from other sugar derivatives?

    <p>It contains a carboxylic acid group derived from glucose. (D)</p> Signup and view all the answers

    Which statement accurately describes D-glucaric acid?

    <p>It is derived from D-glucose and is both water-soluble and optically active. (D)</p> Signup and view all the answers

    Which characteristic is not associated with D-glucaric acid?

    <p>It is derived from D-mannose. (C)</p> Signup and view all the answers

    Which feature differentiates D-glucaric acid from other dicarboxylic acids?

    <p>Its ability to be optically active. (B)</p> Signup and view all the answers

    Which structural feature is crucial for the properties of D-glucaric acid?

    <p>The combination of both carbonyl and hydroxyl groups. (A)</p> Signup and view all the answers

    What role does the hydroxyl carbon play in D-glucaric acid?

    <p>It is responsible for the molecule's hydrophilicity. (B)</p> Signup and view all the answers

    What is maltose primarily composed of?

    <p>2 α-glucose molecules (D)</p> Signup and view all the answers

    Which statement correctly describes maltose?

    <p>It is formed from the hydrolysis of starch. (B)</p> Signup and view all the answers

    Which of the following sugars is not classified as a disaccharide?

    <p>Glucose (D)</p> Signup and view all the answers

    What alternative name is commonly used for maltose?

    <p>Malt sugar (D)</p> Signup and view all the answers

    Which structural characteristic is unique to maltose?

    <p>Forms through an α-1,4 bond linkage (D)</p> Signup and view all the answers

    What distinguishes homodisaccharides from heterodisaccharides?

    <p>Homodisaccharides consist of one type of monosaccharide, while heterodisaccharides consist of different types. (B)</p> Signup and view all the answers

    Which of the following is an example of a homodisaccharide?

    <p>Maltose (B)</p> Signup and view all the answers

    What defines heterodisaccharides compared to homodisaccharides?

    <p>They can be made from one or more types of monosaccharides. (A)</p> Signup and view all the answers

    Which of the following statements about maltose is correct?

    <p>Maltose consists of two glucose molecules linked together. (C)</p> Signup and view all the answers

    Which of the following best categorizes maltose within the context of saccharides?

    <p>It is a homodisaccharide composed of two identical monosaccharides. (D)</p> Signup and view all the answers

    Which property distinguishes anomeric carbon from free carbon in sugars?

    <p>Anomeric carbon is involved in forming glycosidic bonds. (B)</p> Signup and view all the answers

    What characteristic does sucrose possess in relation to its structure?

    <p>It is a non-reducing sugar. (B)</p> Signup and view all the answers

    Which statement is true regarding the linkage of carbohydrates that involves anomeric carbon?

    <p>Linkages involving anomeric carbon are often found in disaccharides. (C)</p> Signup and view all the answers

    In carbohydrate chemistry, which factor is critical for the classification of sugars as reducing or non-reducing?

    <p>The configuration of the anomeric carbon. (D)</p> Signup and view all the answers

    What impact does the presence of anomeric carbon have on carbohydrate functionality?

    <p>It allows for greater structural diversity in polysaccharides. (B)</p> Signup and view all the answers

    Study Notes

    Lactose Intolerance

    • Low lactase enzyme activity leads to undigested lactose
    • Undigested lactose ferments in the colon
    • Fermentation produces large amounts of CO2, H2, and irritable organic acids
    • These gases and acids cause abdominal cramps and diarrhea

    Aldaric Acids

    • Aldaric acids contain both a carbonyl group and a hydroxyl group on the last carbon
    • D-glucaric acid is an example of an aldaric acid derived from D-glucose
    • Aldaric acids are 6-carbon sugar acids
    • They are water soluble and optically active

    Disaccharides

    • Disaccharides are formed by the condensation of two monosaccharides
    • Common disaccharides:
      • Maltose: α 1-4 glycosidic bond between two α-glucose molecules
      • Cellobiose: β 1-4 glycosidic bond between two β-glucose molecules
      • Lactose: β 1-4 glycosidic bond between α-glucose and β-galactose
      • Sucrose: α 1-β 2 glycosidic bond between α-glucose and β-fructose

    Reducing Sugars

    • Reducing sugars have a free anomeric carbon
    • They can reduce other compounds by donating electrons
    • Maltose, lactose, and cellobiose are reducing sugars
    • Sucrose is a non-reducing sugar

    Starch Degradation

    • Starch is a polymer of glucose
    • Amylase hydrolyzes starch into dextrins, maltose, and glucose
    • Dextrins are branched polymers of glucose
    • Cellulose is a linear polymer of glucose with β 1-4 glycosidic bonds
    • Cellulose is not digestible by humans

    Lactase Deficiency

    • Lactase deficiency leads to lactose intolerance
    • Symptoms include abdominal cramps, diarrhea, and gas
    • It occurs when the body does not produce enough lactase, an enzyme that digests lactose
    • Lactose intolerance is a common condition, particularly in adults

    Uronic Acids

    • Formed when the primary alcohol of an aldose is oxidized to a carboxylic acid
    • Example: D-glucuronic acid from glucose
    • Water soluble and optically active

    Aldaric Acids

    • Dicarboxylic acids
    • Both the carbonyl and the last carbon atom of an aldose are oxidized to carboxylic acid groups.
    • Example: D-glucaric acid from D-glucose

    Disaccharides

    • Formed by the reaction of two monosaccharides
    • Joined by a glycosidic bond
    • Can be homodisaccharides or heterodisaccharides
    • Homodisaccharides are composed of the same monosaccharide units
    • Heterodisaccharides are composed of different monosaccharide units

    Maltose

    • Has the other name "Malt sugar"
    • Is a homodisaccharide composed of two α-glucose molecules linked by an α(1→4) glycosidic bond
    • Important as a component of maltose syrup.

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