Biochemistry: Structure of Carbohydrates
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Questions and Answers

What is the primary function of D-Ribose in the human body?

  • Structural support
  • Energy storage
  • Nucleic acid formation (correct)
  • Intercellular communication

    • Which of the following monosaccharides is NOT linked by glycosidic bonds?

  • D-Lyxose (correct)
  • D-Glucose
  • D-Ribose
  • D-Fructose

    • What is the consequence of a failure to metabolize D-Galactose in the body?

  • Histamine release
  • Galactosemia (correct)
  • Insulin resistance
  • Hemolytic anemia

    • Which sugar acid is specifically produced by the oxidation of the hydroxyl carbon?

    <p>D-Galactose</p> Signup and view all the answers

    What role do glycosyltransferases play in carbohydrate biochemistry?

    <p>Forming glycosidic linkages</p> Signup and view all the answers

    What is the major polysaccharide found in the shells of insects and crustaceans?

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

    What happens to D-Fructose in the liver after its consumption?

    <p>It is converted to glucose</p> Signup and view all the answers

    Which of the following carbohydrates is a key structural component in bacterial cell walls?

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

    What is the initial step in the metabolism of sugars?

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

    Which carbohydrate is used primarily by muscles for ATP generation during contraction?

    <p>Muscle glycogen</p> Signup and view all the answers

    Which sugar is a deoxy sugar that is crucial for DNA?

    <p>2-deoxyribose</p> Signup and view all the answers

    Which of the following compounds is NOT classified as an epimer?

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

    What role does glucuronic acid play in metabolism?

    <p>It is involved in bilirubin metabolism.</p> Signup and view all the answers

    Which carbohydrates are examples of sugar alcohols?

    <p>Ribose and Xylitol</p> Signup and view all the answers

    Which carbohydrate structure is primarily made of amylose and amylopectin?

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

    Which of the following accurately describes isomers?

    <p>Compounds that have the same chemical formula but different structures.</p> Signup and view all the answers

    Which term refers to stereoisomers that differ only at one asymmetric carbon?

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

    What is the common chemical formula of fructose, glucose, mannose, and galactose?

    <p>C6H12O6</p> Signup and view all the answers

    Which statement about sugar alcohols is correct?

    <p>They are monosaccharides reduced at the carbonyl carbon.</p> Signup and view all the answers

    Which of the following options is NOT a component of proteoglycans?

    <p>Ascorbic Acid</p> Signup and view all the answers

    What term describes carbohydrates that are connected to non-carbohydrate structures?

    <p>Complex carbohydrates</p> Signup and view all the answers

    Which statement correctly describes the characteristic of D-sugars in humans?

    <p>D-sugars are the majority of sugars found in humans.</p> Signup and view all the answers

    Which of the following correctly defines racemases?

    <p>They are enzymes that interconvert D- and L- isomers.</p> Signup and view all the answers

    What does the term 'enantiomers' refer to?

    <p>Isomers that are mirror images of one another.</p> Signup and view all the answers

    What does dextrorotatory (D) indicate in terms of polarized light?

    <p>The light is rotated clockwise.</p> Signup and view all the answers

    What represents the main difference between N-glycoside and O-glycoside structures?

    <p>N-glycosides attach the -NH2 group; O-glycosides attach the -OH group.</p> Signup and view all the answers

    Which of the following is true about the classification of sugars?

    <p>All sugars are either D-sugars or L-sugars.</p> Signup and view all the answers

    What primarily distinguishes complex carbohydrates from simple carbohydrates?

    <p>Complex carbohydrates are linked to non-carbohydrate structures.</p> Signup and view all the answers

    Which of the following accurately reflects the relationship between D-sugars and their ability to rotate light?

    <p>Most D-sugars are classified as dextrorotatory.</p> Signup and view all the answers

    Which of the following best describes the functional nature of glycosaminoglycans?

    <p>They serve as lubricants and structural elements in tissues.</p> Signup and view all the answers

    What distinguishes aldoses from ketoses in carbohydrates?

    <p>Aldoses have an aldehyde as their most oxidized functional group.</p> Signup and view all the answers

    Which statement about disaccharides is true?

    <p>They are formed from two monosaccharides.</p> Signup and view all the answers

    Which of the following carbon counts represents a pentose?

    <p>5</p> Signup and view all the answers

    Which of the following groups can be found in carbohydrates besides hydroxyl groups?

    <p>Phosphate groups</p> Signup and view all the answers

    What is a characteristic feature of polysaccharides?

    <p>They consist of more than 10 monosaccharides.</p> Signup and view all the answers

    Which of the following is an example of a hexose?

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

    What is the primary characteristic of triodes in carbohydrate classification?

    <p>They consist of 3 carbon atoms.</p> Signup and view all the answers

    What common feature do glycosaminoglycans share?

    <p>They contain sulfate groups.</p> Signup and view all the answers

    Which of the following substances is classified as a nonose?

    <p>Neuraminic acid</p> Signup and view all the answers

    What type of functional group is typically associated with ketoses?

    <p>Keto groups</p> Signup and view all the answers

    Study Notes

    Overview of Carbohydrates

    • Carbohydrates are the most abundant organic molecules in nature.
    • Exist as polyhydroxylated aldehydes or ketones.
    • Minimum structure requires at least three carbon atoms, a hydroxyl group, and typically an aldehyde or ketone.
    • Classified into monosaccharides, disaccharides (two monosaccharides), oligosaccharides (three to ten monosaccharides), and polysaccharides (more than ten monosaccharides).

    Types of Monosaccharides

    • Triose: Glyceraldehyde (3 carbons)
    • Tetroses: Erythrose (4 carbons)
    • Pentoses: Include Ribose (5 carbons), vital for nucleic acids and as a coenzyme.
    • Hexoses: Include Glucose (6 carbons), primary energy source; important for metabolism.
    • Heptoses: Sedoheptulose (7 carbons).
    • Nonoses: Neuraminic acid (9 carbons), important in cell recognition.

    Key Functional Groups

    • Can contain phosphate (e.g., UDP-glucose), amino (e.g., Glucosamine), or sulfate groups (e.g., Chondroitin sulfate).
    • Aldoses have an aldehyde group (e.g., Glyceraldehyde).
    • Ketoses have a keto group (e.g., Dihydroxyacetone).

    Functions of Carbohydrates

    • Provide energy and are storage forms (glycogen).
    • Act as metabolic intermediates and form components of nucleotides in DNA and RNA.
    • Contribute to cell membranes, immunity, and structural roles in organisms, such as cellulose in plants and chitin in shells.

    Sugar Metabolism and Important Compounds

    • Monosaccharides linked by glycosidic bonds.
    • Initial step in sugar metabolism is phosphorylation.
    • Glucosamine is derived from chitin, significant in insect shells.
    • Galactosamine is found in polysaccharides such as cartilage.

    Glycogen and Energy Storage

    • Glycogen serves as the primary storage carbohydrate in animals, mainly in liver and muscle.
    • Liver glycogen maintains blood glucose levels during fasting; muscle glycogen helps generate ATP for contraction.

    Sugar Acids and Their Role

    • Produced from oxidation of specific carbons (e.g., Ascorbic Acid and Glucuronic Acid).
    • Glucuronic Acid is vital in proteoglycans and bilirubin metabolism.

    Unique Sugars and Isomerism

    • Deoxy sugars have a hydrogen atom instead of a hydroxyl group (e.g., 2-deoxyribose).
    • Sugar alcohols result from the reduction of carbonyls in monosaccharides.
    • Isomers have identical molecular formulas but different structures (e.g., Fructose, Glucose).
    • Epimers differ at one asymmetric carbon (e.g., Glucose and Galactose are C-4 epimers).

    Enantiomers and Their Importance

    • Enantiomers are mirror-image isomers, defined as D- and L- sugars based on light polarization direction.
    • D-sugars dominate in human biochemistry, with enzymes (racemases) facilitating interconversion.

    Complex Carbohydrates

    • Complex carbohydrates link to non-carbohydrate structures, such as nucleotides and glycoproteins.
    • N-glycosidic bonds connect amino groups of non-carbohydrates to sugars.
    • O-glycosidic bonds link hydroxyl groups of non-carbohydrates to sugars.

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    Related Documents

    Biochemistry - Structure of Carbohydrates PDF

    Description

    Explore the intriguing world of carbohydrates in biochemistry. This quiz delves into different types of carbohydrates, their structures, and examples across various carbon counts. Test your knowledge on trioses, tetroses, and more!

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