Unit 1: Chemistry of Life
1.1 Water and Hydrogen Bonds
 Water is polar, meaning it has a partially positive area and a
partially negative area.
 Polar molecules can hydrogen bond with other polar
molecules, when the partial + of one attracts the partial – of
the other molecule.
o Cohesion – water’s attraction to other water
molecules
o Adhesion – water’s attraction to other polar
substances
o Surface tension – The relative difficulty in breaking
through water’s surface due to hydrogen bonds between water molecules
 Non-polar molecules have no partial charges, and clump together because they are hydrophobic (waterfearing)
1.3 Introduction to Biomolecules
 Hydrolysis
o The breaking of covalent bonds that join together polymers (big  small)
o Requires the breaking (lysis) of a water molecule to stabilize the products
 Dehydration synthesis
o The formation of covalent bonds between monomers (building of a polymer) (small  large)
o Results in the formation of a water molecule as a byproduct.
1.4 Properties of Biomolecules
Carbohydrates
Lipids
Proteins
Nucleic Acids
Fatty Acids
Monomer
Monosaccharides
Amino Acids
Nucleotides
Names
Glycerol
Polymer
Polysaccharides
Lipids
Proteins, Polypeptides Nucleic Acids
Names
C, H, O
C, H, O, N
Primary
C,H,O (in 1:2:1 ratio)
C, H, O, N, P
Elements
(Phospholipids have P) (Some have S)
Long hydrocarbon
(usually) Ring-like
structure
chains
Saturated – no C-C
double bonds
Unsaturated – Contain
double bonds, which
give the molecule
fluidity
Structure
Examples
Sugars, starch,
glycogen, cellulose
Fats, Oils, Butter
Polarity
Polar - due to the
presence of OH groups
Nonpolar - due to the
long hydrocarbon
chains
A central C bonded to:
 H atom
 NH2 (Amino)
 COOH (Carboxyl)
 R group
(Functional)
Hemoglobin, Catalase,
Lipase
Polar or Nonpolar depending on the R
group (see back)
Nucleotide contains:
-sugar
-phosphate group
-nitrogen base
DNA, RNA
Polar - due to the
sugar, negatively
charged phosphate

Types of amino acids (based on R-group)
o Nonpolar – R group contains mainly C-H bonds
o Polar – contains O-H, N-H, or S-H bonds
o Basic – positively charged
o Acidic – negatively charged
1.5 Structure and Function of Biomolecules (protein structure)
 The structure of a molecule determines its function. Changing the structure of a molecule can change its
function
 Proteins have 4 structural levels:
o Primary (1°)
 The sequence of amino acids
 Held together by strong covalent bonds
 Can only change due to mutations in the DNA or
RNA code
o Secondary (2°)
 alpha helices or beta-pleated sheets
 held together by weak hydrogen bonds (between the amine and carboxyl groups
o Tertiary (3°)
 Folding of the protein caused by interactions between R-groups of the amino acids
 Strong disulfide bridges form between cysteine amino acids
 Slightly weaker hydrophobic interactions between nonpolar (hydrophobic) amino
acids hiding from polar and/or charged (hydrophilic) amino acids
 Weaker ionic bonds between basic and acidic amino acids
 Weak hydrogen bonds between polar amino acids
 Weak ionic and hydrogen bonds can be affected by high temperatures and changes in
pH
o Quaternary (4°)
 When 2 proteins (polypeptides) come together to form a multi-protein complex
 Held together by weak bonds (similar to tertiary level bonding) that can be affected
by temperature and pH
1.6 Nucleic Acids
 Monomers contain 3 components:
o Sugar (Deoxyribose or
Ribose)
o Phosphate group (always
the same)
o Nitrogen base (4
different types)
 DNA is double-stranded and antiparallel and is defined by the 3’
and 5’ end designations (shown below)
 Double-stranded DNA is held together by hydrogen bonds between
complementary bases (C and G) (A and T)
 Have an overall negative charge due to the negative phosphate
group
 Differences between DNA and RNA
o DNA has deoxyribose sugar, RNA has ribose sugar
o RNA has base Uracil (U) and DNA has base Thymine (T)
o DNA is usually double-stranded, RNA is usually single-stranded
pH
 pH lower than 7 is acidic – Acids have high concentrations of H+ (protons)
 pH higher than 7 is basic – Bases have low concentrations of H+ (protons)