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Four Major Types of Biological
Macromolecules
Type of Polymer
Monomers making up
Polymer
I. Carbohydrates
(Polysaccharides)
Monosaccharides
II. Lipids
Fatty acids and
glycerol
III. Proteins
Amino acids
IV. Nucleic Acids
Nucleotides
Example
Sugars,
Starch,
Cellulose
Fats, steroids,
cholesterol
Enzymes,
structural
components
DNA, RNA
I. Carbohydrates
• Made from monomers called
monosaccharides (simple sugars)
– Short term energy
– Glucose: most common, used directly in cellular
respiration to make ATP (energy)
Figure 5.3 The structure and classification of some monosaccharides
Disaccharides
Polysaccharides:
Complex Carbohydrates
• 3 major types made from monomers of
glucose:
– Starch: energy storage in plants
– Glycogen: energy storage in animals
– Cellulose: structural molecules in plants
Figure 5.6 Storage polysaccharides
Figure 5.7a Starch and cellulose structures
Figure 5.7b,c Starch and cellulose structures
Figure 5.8 The arrangement of cellulose in plant cell walls
II. Lipids
• Not true polymers
• Composed of mostly glycerol and fatty acids
• Includes
– Fats: energy storage
– Phospholipids: membranes
– Steroids: hormones, cholesterol
Fats are made of one glycerol and three fatty acids
Double bonds
between
carbons
cause
kinks in
hydrocarbons.
H2C
CH2
H2C
CH2
H2C
CH
Kink
CH
H2C
H2C
H2C
CH2
CH2
Unsaturated
fatty acid
Double bonds, fewer
H atoms
Saturated
fatty acid
No Double bonds,
maximum H atoms
Figure 5.11 Examples of saturated and unsaturated fats and fatty acids
Phospholipids are made of one phosphate group and
2 fatty acids
Phospholipids are amphipathic
Figure 5.13 Two structures formed by self-assembly of phospholipids in aqueous
environments
Steroids consist of a complex carbon ring structure
Figure 5.14 Cholesterol, a steroid
Figure 4.8 A comparison of functional groups of female (estradiol) and male
(testosterone) sex hormones
III. Proteins
• Made from monomers called amino acids
• Very different structures, very different functions
H
Amino
group
H2N
C
R
Side chain
O
C
Carboxyl
group
OH
The R groups of an
amino acid may be
hydrophobic or
hydrophilic
Amino acids are joined together by a
dehydration reaction
H
H2N
C
Carboxyl
group
O
C
OH
Amino
group
H
+
N
C
CH3
H2O
H2N C C
C
OH
H
H
O
H
H O
H H
O
N C C
H
CH3
Peptide
bond
OH
Many amino acids joined together = Polypeptide chain
N-terminus
H
C-terminus
H H
O H H
O H
H
O H H
O H
N
C N
C
C
C
C
C
H
C
CH3
N
N C
CH2
CH2
OH
C OH
H
O H H
O H H
O
H H
O
N C
C N C
C N
C N C
C
CH2
CH
H3C
CH3
C
CH2
CH2
SH
O
OH
OH
The sequence of amino acids in the polypeptide chain = the
primary structure of a protein
Hydrogen bonds between amino acids leads to the secondary
structure of a protein
Two common
secondary
structures are the
-helix and pleated sheet
Further folding of the polypeptide chain contributes to the
tertiary structure of a protein
The joining of more than one polypeptide chain leads to the
quaternary structure of proteins
Heat (energy) can break up the structure of a protein
Table 5.1 An Overview of Protein Functions
Type
Role
Example
Enzyme s
Quickens chemi cal r eact ions
Over 10 0 0 ty pes o f
enzyme s e xist
Hormones
Chemical me sseng ers
Human Growt h hormone
Tr ansport
Move oth er molecules
Hemoglobin- m ov es O 2
Cont ract ile
Movement
Prot ect ive
Healing, d ef ense against
predato rs
Struct ural
Mechanical supp ort
Storage
Stores nu t rients
Ovalbumin ( egg wh it es)
To xi ns
Def ense, pre dat ion
Snake ve no m
Communicat ion
Cell signaling
Recept ors o n cell sur fa ce
Myosin & a ct in- a llow
muscle contr act ion
Fibrino gen (b lood c lott ing)
Anti bodies
Kerat in (h air), collagen
( carti lidge)
IV. Nucleic Acids
• Nucleic acids (DNA and RNA) are made of
monomers called nucleotides
RNA Nucleot ide
DNA Nucleot ide
OH
OH
5’
HO – P --- O –CH 2
A, G,
T, or C
O
O
P
1’
Phosphate 3'
2'
OH H
Sugar
Nitrogenous
base
CH2
O
A, G,
U, or C
O
O
4’
group
HO
4'
Phosphate
group
1'
2'
3'
OH
OH
Sugar
Nitrogenous
base
Figure 5.29 The components of nucleic acids
Figure 3.17b
3´
5´
DNA is a
double
helix.
5´
5´
3´
T
T
A
G
C
C
G
T
A
A
T
A
A
C
G
G
C
A
T
T
A
C
G
C
T
A
T
G
C
T
A
G
C
T
A
Cartoon of
base pairing
5´
3´
A
G C
C G
T
T
C
G
G
A T
A
T
A
A
T
G
C
A
3´
G
T
3´
5´
Cartoon of
double helix
5´
3´
Space-filling model of
double helix
Nucleic acids store the information to make proteins
Figure 5.30 The DNA double helix and its replication