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Chapter 14 Carbohydrates

14.1 Carbohydrates

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Carbohydrates

Carbohydrates are• a major source of energy from

our diet. • composed of the elements C,

H and O.• also called saccharides, which

means “sugars.”

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Carbohydrates

Carbohydrates • are produced by

photosynthesis in plants. • such as glucose are

synthesized in plants from CO2, H2O, and energy from the sun.

• are oxidized in living cells to produce CO2, H2O, and energy.

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Types of Carbohydrates

The types of carbohydrates are • monosaccharides, the simplest carbohydrates. • disaccharides, which consist of two monosaccharides.• polysaccharides, which contain many monosaccharides.

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Monosaccharides

Monosaccharides consist of • 3-6 carbon atoms typically.• a carbonyl group (aldehyde or ketone).• several hydroxyl groups.

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Aldoses

Aldoses are monosaccharides • with an aldehyde group • with many hydroxyl (-OH)

groups.triose (3C atoms)tetrose (4C atoms)pentose (5 C atoms)hexose (6 C atoms)

O ║

C─H aldose │ H─ C─OH │ H─ C─OH │

CH2OH

Erythose, an aldotetrose

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Ketoses

Ketoses are monosaccharides • with a ketone group • with many hydroxyl (-OH)

groups.

CH2OH │ C=O ketose │ H─ C─OH │ H─ C─OH │

H─C─OH │ CH2OH

Fructose, a ketohexose

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Learning Check

Identify each as aldo- or keto- and as tetrose, pentose, or hexose:

A B

H

CH2OH

OHC

H

H

H

OH

OH

OH

C

C

C

HC

O

CH2OH

HHO

CH2OH

O

H OHC

C

C

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Solution

A. aldohexose

B. ketopentose