This document discusses carbohydrates and their classification. Carbohydrates are produced by plants through photosynthesis and are converted into glucose for human energy. Carbohydrates are classified as simple or complex, with simple carbohydrates being monosaccharides like glucose, fructose, and galactose or disaccharides like sucrose, lactose, and maltose composed of two monosaccharides. Complex carbohydrates are polysaccharides like starch stored in plants and glycogen stored in animal liver and muscle. The document also distinguishes between naturally occurring sugars in foods and added sugars in processed foods and sweets.

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Carbohydrates,
Sugars, and
Starches

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What Are Carbohydrates?
 Produced by plants during photosynthesis
 After eating plant foods, humans convert the carbohydrates
into glucose
 Glucose
• Most abundant carbohydrate
• Preferred source of energy for the blood, brain, and
nervous system

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Classification of Carbohydrates
 Simple carbohydrates
• Monosaccharide- one sugar
• Disaccharide- 2 sugars
• Perceived as sweeter than complex carbohydrates
- Mixes with saliva and reacts with taste buds
 Oligosaccharides 3-10 sugars
 Complex carbohydrates
• Polysaccharides

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Monosaccharides
 Three nutritionally important monosaccharides
• Glucose
• Fructose
• Galactose

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Monosaccharides
 Glucose
• Most abundant monosaccharide in the body
- Is the preferred and main source of energy for the
brain and red blood cells
• Part of every disaccharide

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Monosaccharides
 Fructose
• Sweetest of natural sugars
• Found abundantly in fruits

7. Figure 4.2
The Structural Differences between Glucose,
Galactose, and Fructose

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Disaccharides
 Three Disaccharides
• Sucrose Table sugar
• Lactose found in milk
• Maltose

9. Figure 4.3
Monosaccharides Link to Form Disaccharides

10. Condensation / dehydration synthesis
is the process of joining two molecules, or
compounds, together following the removal of
water.

11. Hydrolysis - Breaking down large molecules into smaller
molecules.
(reverse reaction of condensation )

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Polysaccharides
 Starch
• Plants store glucose in chains of starch

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Polysaccharides
 Glycogen
• Storage form of glucose in animals
• Stored in liver and muscle
• Long, branched chains of glucose

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Natural versus Added Sugar
 Naturally occurring sugar
• Sugars such as fructose and lactose found naturally in
foods
• Tend to be nutrient dense
 Added sugar
• Sugars added to processed foods and sweets
• Empty calories

16. Figure 4.18
Slices of an Orange versus Orange Slices

17. Figure 4.19
Finding Added Sugars on the Label

18. Figure 4.20
Americans Drink the Majority of Their Sugar