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Problem 2a
Draw the structures of an aldopentose.
Problem 2b
Draw the structures of a ketohexose.
Problem 5
Aldoheptoses have five chiral carbon atoms. What is the maximum possible number of aldoheptose stereoisomers? Draw all of the aldoheptose stereoisomers.
Problem 6a
Draw the enantiomer of the following monosaccharides, and in each pair identify the D sugar and the L sugar.
a.
Problem 6b
Draw the enantiomer of the following monosaccharides, and in each pair identify the D sugar and the L sugar.
b.
Problem 7
D-Talose, a constituent of certain antibiotics, has the open-chain structure shown next. Draw d-talose in its cyclic hemiacetal form.
Problem 8
The cyclic structure of D-idose, an aldohexose, is shown in the margin. Convert this to the straight-chain Fischer projection structure.
Problem 9a
Draw the structure that completes the mutarotation reaction between the two cyclic forms of (a) galactose and (b) fructose.
a.
Problem 9b
Draw the structure that completes the mutarotation reaction between the two cyclic forms of (a) galactose and (b) fructose.
b.
Problem 11
In the monosaccharide hemiacetal shown below number all the carbon atoms, identify the anomeric carbon atom, and identify it as the α or β anomer.
Problem 13d
L-Fucose is one of the naturally occurring L monosaccharides. It is present in the short chains of monosaccharides by which blood groups are classified. Compare the structure of L-fucose shown in the margin with the structures of α- and β-D-galactose and answer the following questions.
d. "Fucose” is a common name. Is 6-deoxy-L-galactose a correct name for fucose? Why or why not?
Problem 14
Draw the structure of the α and β anomers that result from the reaction of methanol and ribose. Are these compounds acetals or hemiacetals?
Problem 15
How would you classify the link between the monosaccharides in cellobiose?
Problem 20
During the digestion of starch from potatoes, the enzyme α-amylase catalyzes the hydrolysis of starch into maltose. Subsequently, the enzyme maltase catalyzes the hydrolysis of maltose into two glucose units. Write an equation (in words) for the enzymatic conversion of starch to glucose. Classify each of the carbohydrates in the equation as a disaccharide, monosaccharide, or polysaccharide.
