20. Carbohydrates

Name four important monosaccharides and tell where each occurs in nature.

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.

Describe the differences between mono-, di-, and polysaccharides.

Name a naturally occurring carbohydrate and its source for each type of carbohydrate listed in Problem 20.83.

What are the functional groups and number of carbons in a ketopentose?

Identify the monosaccharide that fits each of the following descriptions:

(a) also referred to as dextrose

Identify the monosaccharide that fits each of the following descriptions:

(a) in combination with glucose produces the disaccharide lactose

Explain the difference between an oligosaccharide and a polysaccharide.

Classify the following carbohydrates as a monosaccharide, disaccharide, oligosaccharide, or polysaccharide:

(a) carageenan, a seaweed extract containing up to 25,000 carbohydrate units

Classify the following carbohydrates as a monosaccharide, disaccharide, oligosaccharide, or polysaccharide:

(a) raffinose, a soluble fiber containing three carbohydrate units

Identify the following as characteristics of soluble or insoluble fiber:

(a) can mix with water

Identify the following as containing soluble or insoluble fiber:

(a) oatmeal

Classify each of the following monosaccharides by the type of carbonyl group and the number of carbons (for example, a monosaccharide with an aldehyde and three carbons is an aldotriose).

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How are the following pairs of carbohydrates, shown in a Fischer projection, related to each other? Are they structural isomers, enantiomers, diastereomers, or epimers?

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