Chapter 5

Structure & Function of Macromolecules

• Macromolecules

• Monomer

• Dimer

• Polymer

• Dehydration synthesis –

(condensation reaction)

removal of a water molecule when 2 simpler substances join

• Hydrolysis –

breaking down compounds by the

addition of water

Organic compounds1) Carbohydrates –

• contain C, H, O

• Short term energy sources

• Ratio of H:O is 2:1

• Examples: sugars, starches

Carbohydrates

a) Monosaccharides –

• sugar monomers

ex: glucose, fructose, galactose

C6H12O6

b) Disaccharides –

• 2 monosaccharides joined by a

glycosidic linkage

ex: lactose, maltose, sucrose

C12H22O11

Dehydration synthesis

c) Polysaccharides -

• 3 or more sugar monomers joined

ex: amylose, glycogen, cellulose, chitin

2) Lipids

• Contain C, H, O

• Ratio of H:O is not 2:1

• Examples: fats, oils, waxes, steroids

• Long-term energy storage

• Glycerol, fatty acids are monomers

Figure 5.10 The synthesis and structure of a fat, or triacylglycerol

• Phospholipids –

– 2 fatty acids, glycerol, PO4 group

– Important in membrane structure

• Cholesterol –

– Basis of other steroids

Phospholipids

Saturated Unsaturated

3) Proteins

• Contain C, H, O, N, sometimes P, S

• Structure, transport, synthesizing hormones,

defense, coordination

• Amino acids are protein monomers

Amino acid

1. Amino group 3. Carboxyl group2. R group

Protein conformationPrimary structure –

polypeptide chains• Secondary structure –

helix, pleated sheets, both due to

H bonds• Tertiary structure –

due to bonding between side chains

H bonds, ionic bonds, disulfide bridges

• Quaternary structure –

2 or more polypeptide subunits join to make functional protein

Figure 5.18 The primary structure of a protein

Secondary (2°) StructureFolds in part of amino acid chain: Hydrogen

bonds

- pleated sheet -helix

Figure 5.22 Examples of interactions contributing to the tertiary structure of a protein

Interactions between 2+ polypeptides

Quaternary (4°) Structure

Protein conformation

Figure 5.17 Conformation of a protein, the enzyme lysozyme

Shape is critical for protein interactions

EXAMPLE:

Hemoglobin•4 Polypeptides•Binds Iron•Oxygen transport

Figure 5.19 A single amino acid substitution in a protein causes sickle-cell disease

• Denaturation –

-protein unravels and loses native conformation

-may be caused by changes in pH, salinity, temperature, or concentration

pH

Heat

Chemicals

What can cause proteins to denature?

4) Nucleic acids

• Contain C, H, O, N, P

• Polymers

• DNA and RNA

• Monomers are nucleotides joined by covalent bonds called phosphodiester linkages

• Function in storage and transfer of

information

Figure 5.29 The components of nucleic acids