LECTURE 5: Macromolecules
•Describe the difference between a monomer and a
polymer
•List the four main macromolecules of biological importance
•Explain what molecules make up a protein, a lipid, a
complex carbohydrate and a nucleic acid
What makes a molecule organic?
• Organic molecules
– Contain carbon
• Inorganic molecules
– Do not contain carbon
Why is carbon so important?
• Known as the building block of life
• Has unique bonding properties
– Has four unpaired electrons in outer energy level
– Can form 4 covalent bonds
What are the possible structures of
carbon molecules?
• Straight chain
• Branched chain
• Ring
What is a polymer?
• Polymer
– Large molecule made of monomers bonded
together
– “Macromolecule”
• Mono = One
• Poly = Many
What are the elements of life?
•
•
•
•
•
•
•
Carbon
Hydrogen
Nitrogen
Oxygen
Phosphorus
Sulfur
“CHNOPS”
What are the four main
macromolecules important to living
things?
• Carbohydrates
• Lipids
– Fats
• Protein
• Nucleic Acids
Carbohydrates
• Composed of carbon, hydrogen, and oxygen
• Include sugars and starches
• Can be broken down to provide a source of
usable chemical energy for cells
Monosaccharides
• Simple sugars are called monosaccharides
• Have five or six carbon atoms
• Examples: glucose, fructose
• Two simple sugars are a disaccharide
• Starches, glycogen, and cellulose are
polysaccharides
Glucose
Starches
• Starches are branched chains of glucose
molecules
Cellulose
• Cellulose is the major building block in plant
cell structure
– Has a straight ridged structure
Lipids
• Lipids are chains of carbon atoms bonded to
oxygen and hydrogen atoms
– Non-polar molecules
• Fats, oils, cholesterol
• Consist of a molecule called glycerol bonded
to a fatty acid
Triglycerides
• Triglyceride: three fatty acids bonded to a
glycerol
– Two types
• Saturated: every place a carbon can be bonded to a
hydrogen it is
• Unsaturated: Fewer hydrogen atoms than possible
Phospholipid
• Cell membranes are made of phospholipids
– Glycerol, two fatty acids, and a phosphate group
• Phosphate group makes a polar head
• Fatty acids are non-polar tails
Proteins
• Proteins are polymers made of amino acid
monomers
• Amino Acids contain carbon, hydrogen,
oxygen, nitrogen, and sometimes sulfur
• There are 20 different amino acids
Amino Acid Structure
• Carbon bonded to:
– a hydrogen
– amino group (NH2)
– a carboxyl group (COOH)
– a side group (R group)
• R groups distinguish the different types of amino acids
Polypeptides
• Amino acids form covalent bonds called
peptide bonds
• Due to these peptide bonds many amino acids
linked together are called polypeptides
• A protein is one or more polypeptides
Interactions of Side Groups
• Some side groups have sulfur that forms
covalent bonds and bends protein
• Side groups can form hydrogen bonds to fold
protein
Nucleic Acids
• Nucleic acids are polymers of DNA/RNA
• Nucleotides are monomers of Nucleic Acids
– Composed of:
• Sugar
• Phosphate group
• Nitrogen-containing molecule called base
DNA
• Holds blueprint for creating proteins