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Which of the following correctly describes the basic nomenclature of carbohydrates?
What type of carbohydrate is characterized by having aldehyde functionality?
Which statement best describes epimers?
Which of the following carbohydrates can be produced from CO2 and H2O during photosynthesis?
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What structural feature differentiates D-Mannose and D-Galactose from D-Glucose?
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Which statement accurately describes the cyclization of monosaccharides?
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What do we call the carbohydrate with the molecular weight of approximately 90 g/mol?
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Which of the following carbohydrates is primarily used as an energy storage molecule?
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What is the role of hydrogen peroxide in the oxidation of organic molecules?
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Which statement accurately describes the glycosidic bond in disaccharides?
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What type of disaccharide is formed when two glucose molecules join via a 1 → 4 bond?
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Which characteristic defines a nonreducing disaccharide?
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How is the concentration of colored compounds measured after oxidation by hydrogen peroxide?
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Which type of bond is more stable, a glycosidic bond or a hemiacetal?
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What is true about the anomeric carbon in a glycosidic bond formation?
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What type of natural carbohydrate structure is commonly found in nature?
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What characteristic makes cellulose a difficult substrate for most animals to metabolize?
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Which microorganism secretes cellulase, allowing them to utilize wood as a glucose source?
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Chitin is primarily found in which of the following?
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Which of the following statements about inulin is true?
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Which property of agar makes it useful in laboratory settings?
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Which polysaccharide is known for being nearly pure fibrous cellulose?
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Which of the following correctly describes the structure of cellulose?
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Which of the following organisms can utilize glucose derived from cellulose due to symbiotic relationships?
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What distinguishes homopolysaccharides from heteropolysaccharides?
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Which type of linkage is primarily found in glycogen chains?
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What is the main function of starch in plants?
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What do dextrins primarily result from?
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Which of the following correctly describes amylopectin?
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What characteristic differentiates the reducing end from nonreducing ends in glycogen?
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Which is a key feature of cellulose structure?
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How do polysaccharides differ from proteins in terms of molecular structure?
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What are the repeating disaccharide units in glycosaminoglycans?
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Which polysaccharide is known for its role in energy storage in plants?
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Heparan sulfate is distinct from heparin because it is:
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What functional role does heparin serve in the body?
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Which of the following best describes the charge characteristics of glycosaminoglycans?
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What is the primary structural role of cellulose in plants?
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Which polysaccharide plays a critical role in providing strength to the exoskeletons of insects and crustaceans?
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Which of the following roles is fulfilled by hyaluronan in vertebrates?
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Which characteristic distinguishes agarose from other polysaccharides listed?
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What is the significance of the meshwork formed by glycosaminoglycans in the extracellular matrix?
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Study Notes
Carbohydrates
- Carbohydrates are produced from carbon dioxide and water through photosynthesis in plants.
- Carbohydrates serve many functions: as a source of energy, energy storage, structural component, and cell signaling molecules.
- Carbohydrates can covalently link to proteins and lipids.
Carbohydrate Nomenclature
- The basic nomenclature is based on the number of carbon atoms in the carbohydrate followed by "-ose."
- For example, a three-carbon carbohydrate is called a triose.
- All carbohydrates initially have a carbonyl functional group.
- Aldehydes are called aldoses, and ketones are called ketoses.
Monosaccharides
- Monosaccharides can be constitutional isomers: aldose is a carbohydrate with aldehyde functionality, ketose is a carbohydrate with ketone functionality
- Monosaccharides can be stereoisomers: epimers are stereoisomers differing at only one chiral center; epimers are not mirror images, therefore not enantiomers; epimers are diastereomers; diastereomers have different physical properties
- Monosaccharides can have straight and ring structures.
Disaccharides and Glycosidic Bond
- Two sugar molecules can be joined via a glycosidic bond between an anomeric carbon and a hydroxyl carbon.
Polysaccharides
- Polysaccharides are typically found in their polymer forms.
- Polysaccharides can be homopolysaccharides (one monomer unit), heteropolysaccharides (multiple monomer units), linear (one type of glycosidic bond), and branched (multiple types of glycosidic bonds).
- Polysaccharides don't have a defined molecular weight.
- Polysaccharides are often in a state of flux, with monomer units added and removed as needed by the organism.
Homopolymers of Glucose: Glycogen
- Glycogen is a branched homopolysaccharide of glucose.
- Glucose monomers form (α1 4) linked chains and branch points with (α1 6) linkers every 8–12 residues.
- Glycogen functions as the main storage polysaccharide in animals.
Homopolymers of Glucose: Starch
- Starch is a mixture of two glucose homopolysaccharides: amylose and amylopectin.
- Amylose is unbranched with (α1 4) linked residues.
- Amylopectin is branched like glycogen, but the (α1 6) linkers occur every 24–30 residues.
- Starch is the main storage polysaccharide in plants.
Dextrins
- Dextrins are low-molecular-weight carbohydrates produced by partial hydrolysis of starch or glycogen.
- They are polymers or D-glucose linked by α-(1→4) or α-(1→6) glycosidic bonds.
- Dextrins can be produced in the gut and during cooking.
- Dextrins can be used as water-soluble adhesives.
Homopolymers of Glucose: Cellulose
- Cellulose is a linear homopolysaccharide of glucose.
- Glucose monomers form (1 4) linked chains.
- Hydrogen bonds form between adjacent monomers and additional H-bonds between chains.
- Cellulose is tough, water insoluble, and the most abundant polysaccharide in nature.
- Cotton is nearly pure fibrous cellulose.
Chitin
- Chitin is a linear homopolysaccharide of N-acetylglucosamine.
- N-acetylglucosamine monomers form (1 4)-linked chains.
- Chitin forms extended fibers similar to those of cellulose.
- It is hard, insoluble, and cannot be digested by vertebrates.
- Chitin is found in cell walls of mushrooms and exoskeletons of insects, spiders, crabs, and other arthropods.
Inulin
- Inulin is a plant polysaccharide made from fructose units with a chain-terminating glucose.
- Inulin has a sweet taste and is present in roots for energy storage.
- Most plants that synthesize inulin do not store energy in the form of starch.
- Inulin is a good source of dietary fiber.
Agar and Agarose
- Agar is a branched heteropolysaccharide composed of agarose and agaropectin.
- Agar is a cell wall component in some seaweeds.
- Agar solutions form gels used in laboratories as a surface for growing bacteria.
- Agarose solutions form gels used in laboratories for DNA separation via electrophoresis.
Glycosaminoglycans
- Glycosaminoglycans are linear polymers of repeating disaccharide units.
- One monomer is either N-acetyl-glucosamine or N-acetyl-galactosamine.
- They are negatively charged due to uronic acids and sulfate esters.
- Glycosaminoglycans form an extended hydrated molecule which minimizes charge repulsion.
- They form a meshwork with fibrous proteins to form the extracellular matrix, connective tissue, and lubricate joints.
Heparin and Heparan Sulfate
- Heparin is a linear polymer of 3–40 kDa.
- Heparan sulfate is a heparin-like polysaccharide attached to proteins.
- They have the highest negative-charge density among biomolecules.
- Heparin prevents blood clotting by activating the protease inhibitor antithrombin.
- Heparin regulates development and blood vessel formation by binding to various cells.
- Heparin can bind to viruses and bacteria, decreasing their virulence.
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Description
This quiz covers the essential aspects of carbohydrates, including their production, functions, and nomenclature. It delves into monosaccharides, isomers, and their roles in biological systems. Test your understanding of these crucial biological molecules.