Four Major Types of Biological Macromolecules

Type of Polymer Monomers making up Polymer

Example

I. Carbohydrates (Polysaccharides)

MonosaccharidesSugars, Starch, Cellulose

II. Lipids Fatty acids and glycerol

Fats, steroids, cholesterol

III. Proteins Amino acidsEnzymes, structural components

IV. Nucleic Acids Nucleotides 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

H2C

H2C

H2C

H2C

H2C

H2C

CH2

CH2

CH

CH

CH2

CH2

Kink

Unsaturatedfatty acid

Saturatedfatty acid

Double bonds between carbons causekinks in hydrocarbons.

Double bonds, fewer H atoms

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   

Figure 5.14 Cholesterol, a steroid    

Steroids consist of a complex carbon ring structure

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

H2NAminogroup

C

Side chain

R

H

CO

OH

Carboxylgroup

The R groups of an amino acid may be

hydrophobic or hydrophilic

H2N

H

H

C C

O

OH

Carboxylgroup

N

H

CH3

C C

O

OHH2N

H

H

C

O

C N CC

HH

CH3

OH

O

Peptidebond

Aminogroup

H

H

H2O

+

Amino acids are joined together by a dehydration reaction

H

H H H H H HO O O H H O H H O

N C C N NC C C C

H CH3CH2

OH

N-terminus

N C C

CH2

C

O

OH

CH2

N C C

CHCH3H3C

CH2

OH

H H O

N C C

H H O

N C C

H H O

N C C

CH2

SH

OH

C-terminus

Many amino acids joined together = Polypeptide chain

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

Ty pe Role Example

Enzymes Quickens chemical reactionsOver 1000 types ofenzymes exist

Hormones Chemical messengers Human Growth hormone

Transport Move other molecules Hemoglobin- moves O2

Contractile MovementMyosin & actin- allowmuscle contraction

ProtectiveHealing, defense againstpredators

Fibrinogen (blood clotting)Antibodies

Structural Mechanical supportKeratin (hair), collagen(cartilidge)

Storage Stores nutrients Ovalbumin (egg whites)

To xins Defense, predation Snake venom

Communication Cell signaling Receptors on cell surface

IV. Nucleic Acids

• Nucleic acids (DNA and RNA) are made of monomers called nucleotides

OH 5’

HO – P --- O –CH2

OO 4’ 1’ 4'

3'

1'

3' 2' 2' H

CH2 HO

OH

O

O O

PA, G,T, or C

A, G,U, or C

OH OH OH

DNA Nucleotide RNA Nucleotide

Sugar Sugar

Phosphate group

Phosphate group

Nitrogenous base

Nitrogenous base

Figure 5.29 The components of nucleic acids

5´

5´ 3´

3´ 3´

3´5´

5´

T

G

C

T

T

T

C

G

A

C

T

G

T

T

G

A

C

G

A

A

G

C

G

T

A

A

C

A

C

A

T A

G C

GC

A T

TA

C G

G

A T

T A

C G

T A

A T

C G

A T

Cartoon ofbase pairing

Cartoon of double helix

Space-filling model ofdouble helix

3´5´

3´5´

Figure 3.17b

DNA is adouble helix.

Nucleic acids store the information to make proteins

Figure 5.30 The DNA double helix and its replication