Macromolecules
Building Blocks
of Life
Macromolecules
• Smaller organic molecules join together to
form larger molecules
– macromolecules
• 4 major classes of
macromolecules:
– carbohydrates
– lipids
– proteins
– nucleic acids
Monomer + Monomer = Polymer
• Carbs, Proteins, Nucleic Acids are made of chainlike repeating units
• Chains of single units (monomers) make polymers
Polymers
• Long molecules built by linking repeating
building blocks in a chain
– monomers
• building blocks
• repeated small units
– covalent bonds
• Why is Carbon so good at this??
How to build a polymer
• Dehydration Synthesis:
• joins monomers by “taking” H2O out
• one monomer donates OH–
• other monomer donates H+
• together these form H2O
H2O
– requires energy & enzymes
HO
H
HO
H
enzyme
Dehydration synthesis
HO
H
How to break down a polymer
• Hydrolysis:
• use H2O to breakdown polymers
• reverse of dehydration synthesis
• cleave off one monomer at a time
• H2O is split into H+ and OH–
– H+ & OH– attach to ends
– requires enzymes
– releases energy
HO
H2O
enzyme
H
Hydrolysis
HO
H
HO
H
1. Carbohydrates (C,H)
• Are sugars and polymers of sugars
– Monosaccharides: one sugar
– Disaccharides: two sugars
– Poly saccharides: more than two sugars
• Store short term energy
Monosaccharides
• Simple sugars that provide short term energy
• Ex: glucose
Disaccharides
• Monosaccharide + Monosaccharide
• Formed via dehydration synthesis
• Ex: sucose
Disaccharide
Polysaccharides
• Complex starches that store short term energy
• Glycogen: hydrolyzed in the liver when sugar supplies
are low
Structural Polysaccharides
• Cellulose: cell walls
• Chitin: exoskeletons
2. Lipids (C, H, O, sometimes P)
• The smallest of the
macromolecules
• Not a true polymer
(different monomers)
– Glycerol head
– Fatty acid tail
• Storage of long-term
energy
Fats
Steroids
Phospholipids
• Cell membranes
phosphorus
3. Proteins (C, H, O, N, sometimes S)
• 3 Dimensional
polymers
– Monomers: amino
acids
– Polymer of amino acids
is called a polypeptide
– Held together by
covalent peptide bond
– Protein is one or more
polypeptides
Many Functions
• Speed up
reactions
• Structure
• Storage
• Transport
• Communication
• Movement
• Defense
Amino Acids
• 20 amino acids
build thousands
of proteins
• Each one has an
amino group,
carboxyl group,
H, and R-group
4 Levels of Protein Structure
• Primary: amino acid
chain held by
peptide bonds
• Secondary:
hydrogen bonds
between H &
carboxyl α-helix or
β-pleated sheet
4 Levels of Protein Structure, cont.
• Tertiary: Rgroups interact
further folding
the protein
• Quaternary:
aggregation of
polypeptides
Just how important is primary structure?
4. Nucleic Acid (C, H, O, N, P)
• Storage of heritable
information
– DNA and RNA
• Monomers:
nucleotides
– Sugar (ribose or
deoxyribose)
– Phosphate group
– Nitrogen base (A, G,
C, T, U)
DNA: deoxyribonucleic acid
• Genetic material
inherited from
parents to
offspring
• Self-replicating
• Does not code
directly for protein
(needs RNA
assistance)
RNA: ribonucleic acid
• Used by the cell to
decode DNA’s
instructions for protein
• DNA  RNA  Protein
• Central Dogma of
Genetics