Transcript Ch03carbs - Environmental

The Chemical Building Blocks
 3.2 Carbohydrates
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Carbohydrates
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CH2OH
H
O
H
OH
H
H
OH
HO
H
OH
Carbohydrates
energy
molecules
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2006-2007
Carbohydrates
 Carbohydrates are composed of C, H, O
carbo - hydr - ate
CH2O
(CH2O)x
C6H12O6
 Function:
energy
 raw materials
materials
sgar sugar

energy storage
 structural

sugar sugar sugar sugar sugar sugar
 Monomer: sugars

ex: sugars, starches, cellulose
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Sugars
 Most names for sugars end in -ose
 Classified by number of carbons
6C = hexose (glucose)
 5C = pentose (ribose)
 3C = triose (glyceraldehyde)

CH2OH
H
O
H
OH
6H
HO
H
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OH
Glucose
H
CH2OH
OH
C
O
H
HO
H
5
OH
O
H
HO
H
Ribose
H
H
H
C
OH
C
3OH
H
Glyceraldehyde
Functional groups determine function
carbonyl
aldehyde
carbonyl
ketone
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Sugar structure
5C & 6C sugars form rings in solution
Where do
you find solutions?
In cells!
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Carbons are numbered
Numbered carbons
C 6'
5' C
O
4' C
C1'
energy stored in C-C bonds
C3'
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C2'
Simple & complex sugars
 Monosaccharides
simple 1 monomer sugars
 glucose

 Disaccharides
2 monomers
 sucrose

 Polysaccharides
large polymers
 starch

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CH2OH
H
O
H
OH
H
H
OH
HO
Glucose
H
OH
Building sugars
 Dehydration synthesis
monosaccharides
|
glucose
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|
glucose
disaccharide
|
maltose
glycosidic linkage
Building sugars
 Synthesis
monosaccharides
|
glucose
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|
fructose
disaccharide
|
sucrose
(table sugar)
Polysaccharides
 Polymers of sugars
costs little energy to build
 easily reversible = release energy

 Function:

energy storage
 starch (plants)
 glycogen (animals)

structure = building materials
 cellulose (plants)
 chitin (arthropods & fungi)
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Linear vs. branched polysaccharides
starch
(plant)
energy
storage
glycogen
(animal)
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What does
branching do?
Polysaccharide diversity
 Molecular structure determines function
in starch
in cellulose
isomers of glucose
 structure determines function…

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Digesting starch vs. cellulose
starch
easy to
digest
cellulose
hard to
digest
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enzyme
enzyme
Cellulose
 Most abundant organic
compound on Earth
herbivores can digest cellulose
 most carnivores cannot digest cellulose

 that’s why they
eat meat to get
their energy &
nutrients
 cellulose = roughage
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BIG DEAL!
Who can live
on this stuff?!
Cow
can digest cellulose well;
no need to eat other sugars
Gorilla
can’t digest cellulose well;
must add another sugar
source, like fruit to diet
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Helpful bacteria
 How can cows digest cellulose?

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bacteria live in their gut & help digest
cellulose-rich (grass) meals