INTRODUCTION TO MACROMOLECULES
I.
BUILDING BLOCKS
A. Overview
1. Macromolecules form when smaller molecules (building blocks or subunits) come
together
a) Monomers are joined by covalent bonds to form polymers
B. Building blocks of proteins
1. Amino acids
a) 20 common amino acids
b) Central carbon with attached hydrogen, amino group, carboxylic acid group, and a
R group
C. Building blocks of lipids
1. Fatty acids
a) Long hydrophobic hydrocarbons
2. Glycerol
a) A triose
D. Building blocks of nucleic acids
1. Nucleotides
a) Nitrogenous base
(1) A, T, C, U, and G
b) Pentose sugar
(1) Ribose in RNA
(2) Deoxyribose in DNA
c) Phosphate
E. Building blocks of polysaccharides
1. Monosaccharides
2. (CH2O)n
II. SYNTHESIS AND DEGRADATION
A. Dehydration synthesis
1. Monomers are joined to form polymers by the removal or a water molecule
(dehydration)
a) This results in covalent attachment of the subunits
(1) The bond forms when a hydrogen from one monomer is linked to a hydroxyl group from
another monomer
B. Hydrolysis
1. Macromolecules can be broken down into their subunits by adding a water molecule
across bonds
III. PROTEINS
A. Functions
1. Structural
2. Enzymatic
a) Catalyze chemical reactions
B. Structure
1. Proteins are polymers of amino acids
2. There are 20 common amino
a) Each has a central carbon attached to 4 groups
(1) Hydrogen
(2) Amine
(3) Carboxylic acid
(4) An R group
b) Amino acids differ by their R groups
(1) There are 20 different R groupss.
3. 2 amino acids are connected by dehydration synthesis
a) The covalent bond is called a peptide bond
C. Levels of organization
1. Primary structure
a) Sequence of amino acids.
(1) The 20 different amino acids can be joined in any sequence
(2) This sequence is determined by the DNA sequence of the gene that encodes for that particular
protein
2. Secondary structure
a) Do to interactions of the amino acids near each other
(1) Hydrogen bonds between amino hydrogens and carboxyl oxygens
b) Results in an -helix configuration or a - sheet configuration
3. Tertiary structure
a) The 3-dimensional folding of the polypeptide chain
b) Do to interaction of R-groups of amino acids some distance away from each other
(1) These interactions could be hydrogen bonding, ionic bonding, or covalent bonding.
4. Quaternary structure
a) Interaction between proteins
D. Denaturation
1. Most secondary, tertiary, and quaternary structure bonds are weak
2. The primary structure, formed by covalent bonds, is very stable
a) The amino acid chain can easily be unfolded (denatured) by changes in pH and
temperature
b) When a protein loses its structure, it can no longer perform its function
IV. POLYSACCHARIDES
A. Functions
1.
Energy reserve
a) Glycogen in animals
b) Starch in plants
2. Structure
a) Cellulose in the cell walls of plants and some algae
B. Structure
1. Monomer
a) Monosaccharides
(1) Carbon, hydrogen, and oxygen in a 1:2:1 (CH2O)n.
b) Monosaccharides contain from 3 to 7 carbons
(1) Trioses contain 3 carbons
(a) Example: glycerol
(2) Tetroses contain 4 carbons
(3) Pentoses contain 5 carbons
(a) Example: ribose
(4) Hexoses contain 6 carbons
(a) Example: glucose
(5) Heptoses contain 7 carbons
2. Larger carbohydrates are created by joining together monosaccharides by dehydration
synthesis reactions
a) Disaccharides
(1) 2 monosaccharides are joined
b) Polysaccharides
(1) Polymer of many monosaccharides
V. LIPIDS
A. Function
1. Long term storage of energy
a) Also insulates and cushions major organs
2. Component of membranes
B. Types
1. Fats (lard and butter) are solids at room temperature
2. Oils (vegetable oils) are liquids at room temperature
C. Structure
1. Lipids are composed of glycerol and three fatty acids
a) Two to three fatty acids are bonded to the glycerol by dehydration synthesis
b) Fatty acids can be removed from the glycerol by hydrolysis
2. Fatty acids
a) Hydrocarbon chains with a carboxyl group
(1) Most have 16 - 18 carbons
b) Saturated fatty acids
(1) No double bonds between the carbon atoms
(a) The carbons are saturated with hydrogens
(2) These will result in lipids that are less fluid
c) Unsaturated fatty acids
(1) One or more (polyunsaturated) double bonds between the carbon atoms
(2) These will result in lipids that are more fluid
d) Fatty acids are non-polar and therefore hydrophobic
3. Phospholipids
a) Lipids with two fatty acids and a phosphate group attached to glycerol
b) Amphipathic
(1) Has a hydrophilic head and hydrophobic tail
c) Lipid bilayer
(1) Two layers of phospholipids
(a) Heads face out into the water
(b) Tails face towards each
VI. NUCLEIC ACIDS
A. Function
1. Store genetic information
2. Transfer genetic information during reproduction
3. Controls protein synthesis
4. Types
a) DNA compromises the chromosomes
b) RNA is used in protein synthesis
B. Monomers
1. Nucleic acids are polymers of nucleotides
a) Nucleotides are bonded by dehydration synthesis
2. Nucleotide consists of three parts
a) Sugar
(1) A pentose
(a) Ribose in RNA
(b) Deoxyribose in DNA
b) Phosphate group
c) Base
(1) A, T, C, and G in DNA
(2) A, U, C, and G in RNA
(3) The order of these bases controls the amino acid sequence in proteins
C. Structure
1. Backbone
a) Alternating sugars and phosphate
2. Bases
a) Stick out from the sugars
3. DNA is often double stranded, while RNA can be single stranded, double stranded, or
both