Chapter 1
The Chemistry of Life
Learning Outcomes
• Explain the relationships between atoms,
molecules, elements and compounds.
• Describe the type of chemical bonds.
• Explain the pH scale and its use.
• Relate the characteristics and functions of the
four classes of macromolecules.
• Recognize the importance of nucleic acids in
inheritance.
What role do chemicals play in life?
• Organisms are composed of chemicals.
• Biochemistry plays an important role in
today’s society.
– Causes/treatment of cancer
– AIDS
– Mental illness
1.1 Atoms, Molecules and Compounds
• 1805 John Dalton
determined that every
element is made of
minute particles.
• He also stated several
principles that describe
an atom’s chemical
behavior.
Organisms and Elements
• Organisms are made up
of a limited number of
compounds, of which
water is the most
abundant.
• 97% of the compounds
are made up of only six
elements.
1.2 The Structure of Atoms
• Atoms themselves are built
of many smaller subatomic
particles.
• Protons and neutrons
remain in the nucleus and
electrons are in the cloud in
differing electron shells.
• Atoms of different elements
have different amounts of
subatomic particles, but the
same element can differ in
amounts of neutrons, this is
called an isotope.
1.3 Chemical Reactions
• Chemical reactions
occur in cells of all living
organisms.
– Only way to form new
molecules
– Involves changes in
energy
• Chemical equations
represent these
reactions.
– They all follow the law of
conservation of matter
– Reactions can need
activiation energy
1.4 Chemical Bonds
• Ionic bonds
• Covalent bonds
• Hydrogen bonds
• Water has a polar
covalent bond.
• This becomes important
in the cell because
molecules must dissolve
in order to move easily
between living cells.
15. Ions and Living Cells
• All life processes depend
on ionization.
• Living cells depend on
internal amounts of H+
and OH-, small changes
can influence important
reactions.
• This is described by the
pH scale.
– A logarithmic scale
– Helps regulate chemical
reactions needed for
growth and survival.
Biochemistry
1.6 Organic Compounds and Life
• Organic compounds are
ones that contain carbon.
• Along with water, these
carbon compounds are
also essential to life.
• Carbon atoms combine to
form large complex
molecules called
macromolecules. This
happens through a
process called
polymerization.
1.7 Carbohydrates
• All types of cells contain
carbohydrates.
• Contain C, H and O (fixed
ratio)
• Monosaccharides
– Contain 3-7 carbons in
skeleton
– glucose
• Disaccharides
– Glucose + fructose  sucrose
• Polysaccharides
– Complex carb
– Cellulose and starch
1.8 Lipids
• Fats or oils
• Two primary functions
– Long term energy storage
– Building of structural parts
of cell membranes
• Contain C, H and O (no
fixed ratio)
• Nonpolar
• Saturated vs. unsaturated
• Phospholipids
• Cholesterol
1.9 Proteins
• Contain C, H, O, N and S
• Structural components
of cells
• Messengers/receive
messages
• Defense against disease
• Most essential role is
that of enzymes
Protein Structure
• Proteins are made of smaller
building blocks called amino
acids.
• Bonds are formed between called
peptide bonds. A long chain of
amino acids is then called a
polypeptide. This is the primary
structure.
• The chain then folds or twists to
form a secondary structure and
then folds more to form a tertiary
structure.
• The tertiary structures will
combine to form a complex
quarternary structure.
• The force that controls folding of
the proteins is hydrophobicity.
1.10 Nucleic Acids
• Dictate the amino acid
sequence of proteins
• Source of genetic
information in
chromosomes
• Made of simple units
called nucleotides
• Two types:
– RNA
– DNA
Genetic Coding in Cells
1.1 The Double Helix
• DNA is a double helix
composed of 2 long
chains of nucleotides
– The backbones run in
opposite directions
– The chains are connected
by hydrogen bonds
– The bases pair specifically
• 1953 Watson & Crick
– Proposed a model for the
DNA molecule
– Based on X-ray diffraction
studies of Rosalind Franklin
1.12 The Functions of DNA
• DNA forms genes that
pass from parent to
offspring.
• DNA stores information
in a codethe code is
translated to amino
acids  the amino
acids combine to
become a protein 
the protein performs a
function