Carbohydrates are composed of carbon, hydrogen, and oxygen. They serve as energy storage molecules and structural materials. Monosaccharides like glucose are simple sugars that can combine through dehydration synthesis to form disaccharides like sucrose or polysaccharides like starch and cellulose. The structure of these carbohydrates, whether linear or branched, determines how quickly they can be broken down to release energy. While herbivores can digest starch, cellulose requires bacteria in the digestive system to break it down.

1. Carbohydrates
AP Biology

2. CH2OH
H O
H
H
OH H
HO OH
H OH
Carbohydrates
energy
molecules
AP Biology 2006-2007

3. Carbohydrates
 Carbohydrates are composed of C, H, O
carbo - hydr - ate
CH2O
(CH2O)x
(CH O) C C6H12O6
HO
2 x 6 12 6
 Function:
 energy energy storage
 raw materials structural materials
 Monomer: sugars
 ex: sugars, starches, cellulose
AP Biology sugar sugar sugar sugar sugar sugar sugar sugar

4. Sugars
 Most names for sugars end in -ose
 Classified by number of carbons
 6C = hexose (glucose)
 5C = pentose (ribose)
 3C = triose (glyceraldehyde) H O
CH2OH CH2OH C
H O O H H C OH
H
H
OH 6H H 5 HO 3OH
HO OH HO H H C
H OH OH H H
AP Biology Glucose Ribose Glyceraldehyde

5. Functional groups determine function
carbonyl
aldehyde
carbonyl
ketone
AP Biology

6. Sugar structure
5C & 6C sugars form rings in solution
Where do
you find solutions
in biology?
In cells!
AP Biology
Carbons are numbered

7. Numbered carbons
C 6'
5' C O
4' C C1'
energy stored in C-C bonds
C3' C2'
AP Biology

8. CH2OH
Simple & complex sugars H O
H
H
 Monosaccharides HO
OH H
OH
 simple 1 monomer sugars H OH
 glucose
Glucose
 Disaccharides
 2 monomers
 sucrose
 Polysaccharides
 large polymers
 starch QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
AP Biology

9. Building sugars
 Dehydration synthesis
monosaccharides disaccharide
H2O
| | |
glucose glucose maltose
glycosidic linkage
AP Biology

10. Building sugars
 Dehydration synthesis
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
monosaccharides disaccharide
H2O
| | |
glucose fructose sucrose
(table sugar)
Let’s go to the
videotape!
AP Biology

11. Polysaccharides
 Polymers of sugars
 costs little energy to build
 easily reversible = release energy
 Function:
 energy storage QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
 starch (plants)
 glycogen (animals)
 in liver & muscles
structure
QuickTime™ and a
TIFF (Uncompressed) decompressor

are needed to see this picture.
 cellulose (plants)
 chitin (arthropods & fungi)
AP Biology

12. Linear vs. branched polysaccharides
slow release
starch
(plant)
What does
energy branching do?
storage
glycogen
(animal)
Let’s go to the
fast
AP Biology release videotape!

13. Polysaccharide diversity
 Molecular structure determines function
in starch in cellulose
 isomers of glucose
 structure determines function…
AP Biology

14. Digesting starch vs. cellulose
starch
easy to
digest enzyme
cellulose
hard to
digest
enzyme
AP Biology

15. Cellulose
 Most abundant organic
compound on Earth
 herbivores have evolved a mechanism to
digest cellulose
 most carnivores have not
 that’s why they
eat meat to get
their energy &
nutrients
 cellulose = undigestible roughage
But it tastes
like hay!
Who can live
AP Biology on this stuff?!

16. 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
Regents Biology

17. Helpful bacteria
 How can herbivores digest cellulose so well?
 BACTERIA live in their digestive systems & help digest
cellulose-rich (grass) meals
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Caprophage
Tell I eat
me about QuickTime™ and a
TIFF (Uncompressed) decompressor
the rabbits,
are needed to see this picture.
Ruminants
Regents Biology
WHAT !
again, George!

18. EAT
X
Let’s build some
Carbohydrates!
Regents Biology 2006-2007