Monosaccharides, Disaccharides and Polysaccharides Flashcards
What is a glycosidic bond?
A bond that links a sugar to another molecule.
Ketoses may have the ability to act as reducing sugars. Which process explains this?
Tautomerization
(A rearrangement of bonds, which allows ketoses to undergo keto-enol shifts. This forms aldoses, which can then act as reducing sugars.)
How are glycosidic bonds broken?
Hydrolysis
What are three of the most important disaccharides?
- sucrose
- maltose
- lactose
Which disaccharide(s) are NOT reducing sugars?
Sucrose
Which disaccharide(s) are reducing sugars?
- Maltose
- Lactose
Why is sucrose NOT a reducing sugar?
Because it has NO free hydroxyl (OH) group at its anomeric carbon.
How are disaccharides formed?
The -OH group on the anomeric carbon of one sugar reacts with the -OH group on another sugar to form an acetal (or ketal).
What are three of the most important polysaccharides?
- cellulose (unbranched)
- starch
- glycogen (highly branched)
They are all polymers of the same monosaccharide, D-glucose.
Which polysaccharide is indigestable by humans? Why?
Cellulose
(contains beta linkages which humans do NOT have the enzymes to digest.)
Which kind of linkages/glycosidic bonds are found in cellulose?
β-1, 4 glycosidic linkages
Cellulose is the ONLY polysaccharide with beta linkages!
Which kind of linkages/glycosidic bonds are found in starch?
α-1, 4 glycosidic linkages
Which kind of linkages/glycosidic bonds are found in glycogen?
α-1, 4 with additional α-1, 6 glycosidic linkages
What are two main types of starches?
- amylose (unbranched and linear α-1, 4 linkages)
- amylopectin (branched α-1, 4 and 1,6 linkages)
Which polysaccharide functions as an energy storage unit in animals?
Glycogen
Which polysaccharide is found in plants and functions in strengthening their cell walls?
Cellulose
Which polysaccharide functions as an energy storage unit in plants?
Starch
Which two polysaccharides share all of their glycosidic linkage types in common?
- amylopectin
- glycogen
