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The Structure and
Function of
Macromolecules
Chapter 5
1 -- carbohydrates
Macromolecules:
The Molecules of Life
 Three of the four classes of life’s organic molecules
are polymers:
Carbohydrates
 Proteins
 Nucleic acids

 Lipids are not polymers, just large molecules
 Nucleic Acids and Carbohydrates -- both
monomers & polymers
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The Synthesis and Breakdown of
Polymers
 Monomers form polymers by condensation (or
dehydration) reactions
 Polymers are disassembled to monomers by
hydrolysis
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LE 5-2
LE 5-2
Macromolecules:
The Molecules of Life
 Carbohydrates
 Nucleic Acids
 Proteins
 Lipids
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Carbohydrates – sugars and
polymers of sugars
 Monosaccharides -- single sugars
 Disaccharides – two sugars
 Oligosaccharides -- three to nine sugars
 Polysaccharides -- many sugar building blocks
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Sugars
 Monosaccharides -- CH2O
 Glucose -- most common
 Classified by location of carbonyl group and number
of carbons in skeleton
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LE 5-3
Triose sugars
(C3H6O3)
Pentose sugars
(C5H10O5)
Hexose sugars
(C5H12O6)
Glyceraldehyde
Ribose
Galactose
Glucose
Dihydroxyacetone
Ribulose
Fructose
Though often drawn as a
linear skeleton, in aqueous
solutions they form rings
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glucose
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glucose
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Disaccharides to Polysaccharides
 Formed when a dehydration reaction joins
two shorter saccharides
 Bond
-- glycosidic linkage
1–4
glycosidic
linkage
Dehydration
reaction in the
synthesis of maltose
Glucose
Glucose
Maltose
1–2
glycosidic
linkage
Dehydration
reaction in the
synthesis of sucrose
Glucose
Fructose
Sucrose
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Glycoside Linkage
Between hydroxyl in one monomer and hydroxyl
in another (e.g., 1-4 in Maltose; 1-2 in Sucrose)
1–4
glycosidic
linkage
Dehydration
reaction in the
synthesis of maltose
Glucose
Glucose
Maltose
1–2
glycosidic
linkage
Dehydration
reaction in the
synthesis of sucrose
Glucose
Fructose
Sucrose
Glycoside Linkage
 Two ring forms: alpha () and beta ()
 Note:  glucose == galactose …..
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Glycoside Linkage
 Between hydroxyl in one monomer and
hydroxyl in another
Maltose (malt sugar) = glucose + glucose
 Lactose (milk sugar) = glucose + galactose

http://stefan101blog.wordpress.com/2013/03/20/glycosidic-linkage-in-carbohydrates
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LE 5-5
COMMON DISACCHARIDES:
Sucrose (table sugar) = glucose + fructose
Maltose (malt sugar) = glucose + glucose
Lactose (milk sugar) = glucose + galactose
Dehydration
reaction in the
synthesis of maltose
1–4
glycosidic
linkage
Glucose
Glucose
Dehydration
reaction in the
synthesis of sucrose
Maltose
1–2
glycosidic
linkage
Glucose
Fructose
Sucrose
Oligosaccharides
 Typically short chains (3-9)
 Fructose and Galactose most common monomers
 Often chemical markers
 ABO blood type
 Therapeutic to the gut flora
 Believed to play a part in fertilization
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Polysaccharide
 Structure and
function -determined by
monomers and
positions of
glycosidic linkages
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Carbohydrates serve as fuel and
building material
 Source -- cellular respiration
 Storage -- polysaccharides
 Structural components -- cell walls, microfibrils,
chitin
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Cellular Respiration
and Photosynthesis
© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e
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RESPIRATION
C6H12O6 + O2
CO2 + H2O + ENERGY
ATP
686 kcal/mole (180 grams)
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Glycolysis …. What next?
Glucose
Glycolysis
CYTOSOL
Pyruvate
No O2 present
Fermentation
or Anaerobic
respiration
O2 present -- Aerobic
cellular respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
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Photosynthesis Summarized
6 CO2 + 12 H2O + Light energy  C6H12O6
+ 6 O2 + 6 H 2 O
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Chloroplast
 Gelatinous matrix called the stroma
 Contains prokaryotic ribosomes, DNA
 Carbohydrate synthesis occurs in the stroma
 Folded membranes called thylakoids fill the
stroma and form into stacks called grana
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LE 10-5_2
Light reactions (in the thylakoids) -- split
water, release O2, produce ATP, and
form NADPH
H2O
Light
LIGHT
REACTIONS
ATP
NADPH
Chloroplast
O2
LE 10-5_3
The Calvin cycle (in the stroma) -- forms
sugar from CO2, using ATP and NADPH
H2O
CO2
Light
NADP+
ADP
+ Pi
LIGHT
REACTIONS
CALVIN
CYCLE
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)
Respiration & Photosynthesis
Respiration
C6H12O6 + O2  CO2 + H2O + ENERGY
Photosynthesis
CO2 + H2O  C6H12O6 + O2 + H2 O
Light energy
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Storage Polysaccharides
Chloroplast
Starch
Plants store
surplus starch as
granules within
chloroplasts,
leukoplasts, and
other plastids
1 µm
Amylose
Amylopectin
Starch: a plant polysaccharide 31
Storage Polysaccharides
 Glycogen is the
storage
polysaccharide in
animals
 Humans and
other vertebrates
store glycogen
mainly in liver
and muscle cells
MitochondriaGlycogen granules
0.5 µm
Glycogen
Glycogen: an animal polysaccharide
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Structural Polysaccharides
 Cellulose -- plant cell walls

Chitin -- cellulose-ish
 Polymers of glucose – different glycosidic
linkages
 alpha
glucose – helical
 beta glucose -- straight
In β glucose -- hydrogen bonds form between strands
strands group into microfibrils -- strong building
materials for plants
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LE 5-8
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
0.5 µm
Plant cells
Cellulose
molecules
 Glucose
monomer
Cellulose vs Starch
 Enzymes that digest starch by hydrolyzing
alpha linkages can’t hydrolyze beta linkages in
cellulose
 Cellulose in human food -- insoluble fiber
 Some microbes use enzymes to digest
cellulose
 Many herbivores, from cows to termites, have
symbiotic relationships with these microbes
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Chitin
 exoskeleton of arthropods
 primary component of cell walls in fungi
 structurally – similar to cellulose
 functionally – similar to protein keratin
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Sucralose
Sucrose
Cl
Sucralose
Cl
Cl
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Stevia
Stevioside
Steviol
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Aspartame
 Aspartame is a methyl ester of aspartic acid and
phenylalanine (2 amino acids).
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Saccharine
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