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Chapter 4Chapter 4
The Carbohydrates: Sugars, The Carbohydrates: Sugars, Starches, and FibersStarches, and Fibers
OH N C
C
H
H
H C
H
H
O H C
H
H
N C
H
H
O HH
H
Hydrogen Oxygen Nitrogen Carbon
Ethanol Ethanolamine
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
Simple Carbohydrates (sugars)
Monosaccharides
OCH2OH
HH
OHH
OH
OH
HH
OH
Glucose
Simple Carbohydrates (sugars)
Monosaccharides
OCH2OH
HH
OHH
OH
OH
HH
OH OCH2OH
HOH
HH
OH
OH
HH
OH
Glucose Galactose
Simple Carbohydrates (sugars)
Monosaccharides
OHOH2C
H
OH
H
H
OHOH
CH2OH
Fructose
Simple Carbohydrates (sugars)
Disaccharides
OCH2OH
HH
OH
OH
OH
HH
OHOCH2OH
HH
OHH
OH
OH
H
H
Maltose
Simple Carbohydrates (sugars)
Disaccharides
OCH2OH
HH
OH
OH
OH
HH
OHOCH2OH
HH
OHH
OH
OH
H
H
Maltose
-glycosidic bond
GlucoseGlucose
Simple Carbohydrates (sugars)
Disaccharides
OCH2OH
HH
OH
OH
OH
HH
OHOCH2OH
HH
OHH
OH
OH
H
H
OCH2OH
HH
OHH
OH
OH
HH
OH
2
Glucose
Hydrolysis
Simple Carbohydrates (sugars)
Disaccharides
O
OCH2OH
HH
OHH
OH
OH
H
H
OHOH2C
HOH
H
H
OHCH2OH
Glucose
glycosidic bond
Fructose
Sucrose
Simple Carbohydrates (sugars)
Disaccharides
OCH2OH
HH
OH
OH
OH
HOH
H
OCH2OH
HOH
HH
OH
OH
HH
Glucose
-glycosidic bond
Galactose
Lactose
Complex Carbohydrates
Polysaccharides
(glycogen, starches & fibres)
Glycogen – energy storage in animals
Starches – energy storage in plants
Fibres – provides structure in plants
Complex Carbohydrates
(glycogen versus starches)
OO OOO
O
OOOO
OOO O
O
OOOOOO
Glycogen Starch(amylopectin) and (amylose)
Animals Plants
Hydrolysis (breakdown) of
Complex Carbohydrates
Both glycogen and starches can be broken down by the human
digestive system to give
||
Glucose
Major sources of starch include grains, legumes, and tubers.
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Starch and cellulose molecules compared (small segments)
O
O
O
O
O
O
O
O
O
O
OO
O
O
O
O
O
O
OO
OO
OO
OO
O
O
O
O
Cellulose
Starches
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.
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
Absorption of Monosaccharides
Monosaccharides enter directly into the blood capillaries
Glucose and Galactose are moved across cell membranes byACTIVE TRANSPORT
Fructose moves across my FACILITATED DIFFUSION
Converted toGLUCOSE
The carbohydrates of grains, vegetables, fruits and legumes supply most of the energy in a healthful diet.
Maintaining blood glucose homeostasis
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Diabetes
- related to the function of insulin to regulate glucose levels
Type I (juvenile diabetes)
Type 2 (adult diabetes)
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Foods rich in starch and fiber offer many health benefits.
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
Carbohydrates on Food Labels
Structure of Artificial Sweeteners
SNH
C
O O
O NHSO3H
N
C H
H
OH
OO O CH3
ONH2
Saccharin(450 X)
Cyclamate(30 X)
Aspartame(180 X)
Hydrolysis of Aspartame
N
C H
H
OH
OO O CH3
ONH2
N
C H
H
O OH
H OH
O
ONH2
OH
CH3OH
methanol
aspartic acid
phenylalanine
Sucralose
O
OCH2OH
HCl
H
OH
OH
H
H
OCH2
HOH
H
H
OHCH2 Cl
Cl
O
OCH2OH
HH
OHH
OH
OH
H
H
OHOH2C
HOH
H
H
OHCH2OH
(600 X)
Glucose
Fructose
Sucrose
SugarReplacers
H
C
C
C
C
C
O
OHH
HOH
OHH
CH2OH
H OH
H
C
C
C
C
C
O
HOH
HOH
OHH
CH2OH
H OH
H
C
C
C
C
CH2OH
O
OHH
HOH
OHH
H
C
C
C
C
C
OH
OHH
HOH
OHH
CH2OH
H OH
HH
C
C
C
C
C
OH
HOH
HOH
OHH
CH2OH
H OH
HH
C
C
C
C
CH2OH
OH
OHH
HOH
OHH
H
glucose mannosexylose
sorbitol mannitolxylitol
Dental Caries
(cavities)
©2001 Brooks/Cole, a division of Thomson Learning, Inc. Thomson Learning™ is a trademark used herein under license.
