Download Details about Biomolecules

Carbohydrates-sugars
 Made of C, H,O
 Carb = Carbon hydrate = water Carbohydrate = carbon +
water
 general formula = C H2O 1-2-1 ratio of C to H to O
ribose
C5H10O5
glucose C6H12O6
sucrose C12H22O11
 many carbohydrate names end in -ose
More carbohydrate basics
 Monomer: monosaccharide – one sugar
 Functions of carbohydrates:
 Energy for metabolism (glucose)
 Short term energy storage (glycogen/starch)
 Structure: plants – cell wall animals – exoskeleton
 Source of carbon for other molecules
 Cell surface markers – cell identification
Monosaccharide: Simple Sugars
 Monosaccharides like glucose are the main source of
energy in living things
Disaccharides - 2 sugars
 2 monosaccharides linked together by dehydration
synthesis
- form a glycosidic bond
Examples:
Sucrose – Table Sugar
glucose + fructose
Lactose – Milk Sugar
glucose + galactose
Polysaccharides-Many Sugars
 Polysaccharides are polymers composed of large
numbers of monosaccharides.
- the monosaccharides are joined by dehydration
synthesis

Used for short term
energy storage and
structure
Energy Storage Polysaccharides
 Starch
Chloroplast
Starch
 polymer made up
of glucose
monomers
 Stores glucose in
plants
1 m
Starch: a plant polysaccharide
 Glycogen
 Polymer of glucose monomers
 Is the major storage form of glucose in animals
 Stored in liver and muscle
 More highly branched than
Mitochondria Glycogen
granules
starch – contains more
stored energy
0.5 m
Glycogen
Glycogen: an animal polysaccharide
Starch and Glycogen are Easily
Broken Apart by Hydrolysis
 Allows the stored glucose to be easily used
Structural Polysaccharides
 Cellulose
 Is a polymer of glucose – connected in a
straight unbranched chain
 Multiple strands of cellulose are held together
by hydrogen bonds – makes a rigid structure
 Is a major component of the tough walls that
enclose plant cells
Cell walls
Cellulose microfibrils
in a plant cell wall
Microfibril
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
0.5 m
Plant cells
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
Figure 5.8
OH CH2OH
OH
CH2OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH
2
2OH
H
CH2OH
OH CH2OH
OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH
2
2OH
H
CH2OH
OH
OH CH2OH
O O
O O
OH
OH
OH O
O OH
O O
O
O CH OH
OH CH2OH
2
H
 Glucose
monomer
Cellulose
molecules
A cellulose molecule
is an unbranched 
glucose polymer.
 Cellulose is difficult to digest
 Animals can’t break the bonds between the glucose
molecules –dietary fiber
 Animals that eat plants have bacteria in their stomachs
that can break the bonds of cellulose- allow their hosts
to digest plants
Figure 5.9
 Chitin, another important structural
polysaccharide
 Is a polymer of a form of glucose with an
attached functional group
 Is found in the exoskeleton of arthropods
CH2O
H
O OH
H
H
OH H
OH
H
H
NH
C
O
CH3
(a) The structure of the
chitin monomer.
Figure 5.10 A–C
(b) Chitin forms the exoskeleton (c) Chitin is used to make a
of arthropods. This cicada
strong and flexible surgical
is molting, shedding its old
thread that decomposes after
exoskeleton and emerging
the wound or incision heals.
in adult form.
Other Uses for Carbohydrates
 Cell surface markers – carbohydrates attached to parts
on the cell membrane where they act to identify the
cell
 ABO blood groups
are identified by
carbohydrates on
their surface