Carbohydrates
What are Carbohydrates?
 Put
simply…hydrocarbons.
 Empirical Formula CnH2nOn
 Divided
into three groups
 Monosaccharides
 Disaccharides
 Polysaccharides
Monosaccharides
 Monomers…single
 Let’s
 How
sugar molecules.
build glucose and fructose.
are the molecules different?
 What functional groups are present?
Monomers in Use
 Ribose

and 2-deoxyribose are pentoses
Used in DNA and RNA
 Glucose,
hexoses


Galactose, and Fructose are
Used in plants and animals for energy
Build into larger biological molecules like
insulin.
Disaccharides
 Two
monosaccharides joined by a
glycosidic bond. (ether)
 A water molecule is generated in the
process of bond formation. (condensation
polymerization)
Disaccharides in Use

Sucrose



Lactose



Table Sugar
Let’s build it! Join the glucose and fructose from
earlier.
Milk sugar: glucose and galactose
Lactose intolerant people lack the enzyme
needed to break lactose’s glycosidic bond.
Invert Sugar

Bees use enzymes to break sucrose’s glycosidic
bond to create invert sugar, which is the sweet
flavor in honey.
Polysaccharides
 Strings

of more than 20 monosaccharides.
Starch
 Major
source of food calories consumed by
people



Amylose (in rice!)= linear polysaccharide
Amylopectin = branched polysaccharide
Glycogen = highly branched, stored in muscles
and liver until converted to fat for long term
storage.
Alpha and Beta Linkages
 Starch
and Cellulose are
made of glucose.
 2 isomer forms for
linkagesalpha and beta.
 Starch has alpha
linkages. (cis)
 Cellulose has beta
linkages. (trans)
Food uses of Carbohydrates
 Reducing
sugars react with amino acids in
the Maillard Reaction (causes browning)
 Polysaccharides bind water to thicken
liquids into gels.
 Used to stabilize suspensions, emulsions.
Pectin

Pectin is a polysaccharide
made of galacturonic acid
(galactose) molecules with
beta linkages.

Found in green apples, lime
peel, lemon peel

When heated with sugar at
low pH, branched
polymerization occurs to
create a thick gels.