30 Questions
What is the molecular size of a monosaccharide?
Single polyhydroxy aldehyde or polyhydroxy ketone unit
How many carbon atoms are typically found in naturally occurring monosaccharides?
4-6
Which of the following is NOT a pentose?
Fructose
Which monosaccharide is an important intermediate in glycolysis?
Dihydroxyacetone
Which of the following has a chiral carbon center?
D-Glyceraldehyde
Which type of monosaccharide includes Aldose and Ketose?
-Sorbose
Which type of bond is formed between two monosaccharide units in a disaccharide?
Glycosidic bond
What is the main reason why glucose is considered a reducing sugar?
Presence of an aldehyde group
Which enzyme is responsible for the hydrolysis of maltose under acidic conditions?
Maltase
What type of sugar is lactose commonly known as?
Milk sugar
Which type of sugar has three isomeric forms?
Sucrose
What does the presence of a hemiacetal carbon in glucose contribute to its classification as a reducing sugar?
Capable of reducing other substances
Why do jams and jellies cooked with acid-containing foods taste sweeter than pure sucrose?
The acid content breaks down the sucrose into more glucose and fructose.
Which sugar substitute is synthesized from sucrose by substituting chlorine atoms for hydroxyl groups?
Sucralose
In what way does neotame differ structurally from aspartame?
Neotame has a 3,3-dimethylbutyl group attached to the terminal -NH2 group.
Which type of sugar substitute is 7000 times sweeter than sucrose?
Neotame
What are oligosaccharides?
Carbohydrates containing three to ten monosaccharide units bonded via glycoside linkages.
Which foods naturally contain oligosaccharides?
Onions, cabbage, and broccoli
What is the function of hyaluronic acid?
Lubricating joints and the vitreous humor of the eye
What distinguishes acidic polysaccharides from other polysaccharides?
They contain galacturonic acid
What is the primary function of heparin?
Preventing the formation of blood clots
Which monosaccharides are present in hyaluronic acid?
Glucosamine and Glucuronate
What is the source of pharmaceutical heparin?
Intestinal or lung tissue of pigs and cows
What differentiates hyaluronic acid from heparin in terms of function?
Preventing blood clot formation vs. blood anticoagulant
What is the primary function of insulin in carbohydrate metabolism?
Promote the uptake and utilization of glucose by cells
Which hormone is released when blood-glucose levels are low?
Glucagon
What stimulates the release of insulin?
High blood-glucose levels
Which hormone speeds up the conversion of glycogen to glucose?
Glucagon
What is the core metabolic disorder associated with insulin?
Diabetes
Which hormone is released by the adrenal glands in response to anger, fear, or excitement?
Epinephrine
Study Notes
Hormonal Control of Carbohydrate Metabolism
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Insulin is a 51-amino-acid protein hormone produced by the beta cells of the pancreas that promotes the uptake and utilization of glucose by cells and lowers blood-glucose levels.
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Insulin triggers the release of glucose into cells, increases glycogenesis, glycolysis, and fatty acid synthesis, and is involved in lipid metabolism.
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Insulin is released in response to high blood-glucose levels and is pivotal in the metabolic disorder known as diabetes.
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Glucagon is a 29-amino-acid polypeptide hormone produced by the alpha cells of the pancreas that increases blood-glucose concentrations by stimulating glycogenolysis and gluconeogenesis in the liver.
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Glucagon's effects are opposite those of insulin and are released in response to low blood-glucose levels.
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Epinephrine, also known as adrenaline, is released by the adrenal glands in response to anger, fear, or excitement and stimulates glycogenolysis, releasing glucose from glycogen.
Carbohydrates Classification
- Carbohydrates can be classified based on molecular size into monosaccharides, disaccharides, oligosaccharides, and polysaccharides.
Monosaccharides
- Monosaccharides are carbohydrates that contain a single polyhydroxy aldehyde or polyhydroxy ketone unit and cannot be broken down into simpler units by hydrolysis reactions.
- Naturally occurring monosaccharides have from three to seven carbon atoms, with five- and six-carbon species being especially common.
- Examples of monosaccharides include glyceraldehyde, dihydroxyacetone, ribose, arabinose, xylose, glucose, and fructose.
Disaccharides
- Disaccharides are carbohydrates that contain two monosaccharide units covalently bonded to each other.
- Examples of disaccharides include sucrose (table sugar), lactose (milk sugar), and maltose.
- Disaccharides can be hydrolyzed to produce two monosaccharide units.
Oligosaccharides
- Oligosaccharides are carbohydrates that contain three to ten monosaccharide units bonded to each other via glycoside linkages.
- Examples of oligosaccharides include raffinose, a trisaccharide found in onions, cabbage, and broccoli.
Polysaccharides
- Acidic polysaccharides, such as hyaluronic acid and heparin, are heteropolysaccharides with a disaccharide repeating unit in which one of the disaccharide components is an amino sugar and one or both disaccharide components has a negative charge.
- Hyaluronic acid is used as a lubricant in joints and has a jelly-like consistency in the vitreous humor of the eye.
- Heparin is a small, highly-sulfated polysaccharide used as a blood anticoagulant, preventing the formation of clots in the blood and retarding the growth of existing clots.
Test your knowledge on sugar chemistry and its applications in food preparation. Learn about sucrose hydrolysis, invert sugar formation, and the sweetness of glucose-fructose mixtures compared to sucrose. Explore different sugar patterns and sugar substitutes like saccharin.
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