The Carbohydrates: Sugars, Starches, and Fibers

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Chapter 4

• The Carbohydrates Sugars, Starches, and Fibers

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• Carbohydrates
• most abundant class of compounds found in
  nature
• contain the elements C, H and O
• term CARBOHYDRATES came from fact that these
  compounds could be written as hydrates of
  carbon
• e.g. C6H12O6
  C6(H2O)6

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• Simple Carbohydrates (sugars)
• Monosaccharides

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Simple Carbohydrates (sugars) Monosaccharides
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Simple Carbohydrates (sugars) Monosaccharides
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Simple Carbohydrates (sugars) Disaccharides
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Simple Carbohydrates (sugars) Disaccharides
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Simple Carbohydrates (sugars) Disaccharides
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Simple Carbohydrates (sugars) Disaccharides
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Simple Carbohydrates (sugars) Disaccharides
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Complex Carbohydrates Polysaccharides
(glycogen, starches fibres) Glycogen
energy storage in animals Starches energy
storage in plants Fibres provides
structure in plants
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Complex Carbohydrates (glycogen versus starches)
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Plants
Animals
Starch (amylopectin) and (amylose)
Glycogen
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Hydrolysis (breakdown) of Complex
Carbohydrates Both glycogen and starches can be
broken down by the human digestive system to
give Glucose
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Major sources of starch include grains, legumes,
and tubers.
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Starch and cellulose molecules compared (small
segments)
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Starch digestion in the GI Tract
MOUTH Starches are hydrolysed to smaller and
smaller polysaccharides by enzymes referred to as
AMYLASE.
STOMACH AMYLASE is deactivated due to acidic pH.
SMALL INTESTINE Pancreatic AMYLASE break starch
polysaccharides down more and DISACCHARIDASES
break down disaccharides.
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Fiber in the GI Tract
MOUTH Fibers are mechanically ripped apart by
teeth and moistened. NO ENZYME BREAKDOWN
STOMACH and SMALL INTESTINE NO ENZYME BREAKDOWN
LARGE INTESTINE Bacterial enzymes can break down
small amounts of fiber. FERMENTATION. CAUSES
GAS
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Absorption of Monosaccharides
Monosaccharides enter directly into the blood
capillaries
Converted to GLUCOSE
Glucose and Galactose are moved across cell
membranes by ACTIVE TRANSPORT Fructose moves
across my FACILITATED DIFFUSION
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The carbohydrates of grains, vegetables, fruits
and legumes supply most of the energy in a
healthful diet.
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Maintaining blood glucose homeostasis
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Diabetes - related to the function of insulin to
regulate glucose levels
Type I (juvenile diabetes) Type 2
(adult diabetes)
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Foods rich in starch and fiber offer many health
benefits.
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Carbohydrates on Food Labels
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Structure of Artificial Sweeteners
Cyclamate (30 X)
Saccharin (450 X)
Aspartame (180 X)
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Hydrolysis of Aspartame
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Sucralose
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Sugar Replacers
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Dental Caries (cavities)