1 chapter 16 carbohydrates 16.7 disaccharides 16.8 polysaccharides
Post on 21-Dec-2015
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Disaccharides
A disaccharide consists of two monosaccharides.
Disaccharide Monosaccharides Maltose + H2O Glucose + Glucose
Lactose + H2O Glucose + Galactose
Sucrose + H2O Glucose + Fructose
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Maltose
Maltose is: A disaccharide in
which two D-glucose molecules are joined by an -1,4-glycosidic bond.
Obtained from starch.
Used in cereals, candies, and brewing.
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Lactose
Lactose is: Also called milk
sugar. Composed of
galactose and glucose linked by a -1,4-glycosidic bond.
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Sucrose
Sucrose: Is the disaccharide
known as table sugar. Is composed of glucose
and fructose molecules joined by ,-1,2-glycosidic bond.
Has no isomers because mutarotation is blocked.
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Sweetness of Sweeteners
Sugars and artificial sweeteners differ in sweetness.
Each sweetener is compared to sucrose (table sugar), which is assigned a value of 100.
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Polysaccharides Polysaccharides are
polymers of D-glucose Important polysaccharides
are:
Starch (Amylose and
Amylopectin)
Glycogen
Cellulose
O
OH
CH2OH
OH
OH
OH
D-Glucose
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Amylose, Amylopectin, and Glycogen
Amylose is a continuous chain of glucose molecules linked by -1,4 glycosidic bonds.
Amylopectin is a branched chain of glucose molecules linked by -1,4- and -1,6-glycosidic bonds.
Glycogen is similar to amylopectin, but more highly branched.