Chemistry
of Life
Nature of matter
• Atom is the smallest unit of
matter that cannot be broken
down by chemical means.
• Atoms typically have 1
electron for each proton, so
they are neutral. (Neutral,
meaning no electrical charge.
3 Basic Particles of an Atom
Particle
Charge
Location
Proton
Positive (+)
Nucleus
Neutron
Neutral (0)
Nucleus
Electron
Negative (-)
Electron
Cloud
The electrons are located in
energy levels located outside of
the nucleus where the electrons
can move. These energy levels
are known as the electron cloud.
• An isotope is an atom of
an element that has the
same number of protons,
but a different number of
neutrons.
• Element is a substance made of only
one kind of atom, and it is a pure
substance.
• There are four elements that make
up 96% of the human body:
1.Carbon
2.Hydrogen
3.Oxygen
4.Nitrogen
• Atoms can bond together.
• A compound is a substance made
of the joined atoms of two or more
different elements.
Example: Na+ + Cl-  NaCl
Sodium ion + Chlorine ion  Sodium Chloride
Table Salt
• A force that joins atoms is called a
bond.
• There are two types of bonds, that
we will study.
1.Covalent Bonds
2.Ionic Bonds
• Covalent and Ionic compounds are
alike in that they both fill outer
electron levels.
• Covalent bonds are created
when two or more atoms
share electrons and form a
molecule.
• Molecules are held together
by covalent bonds.
• Examples: H2O, CO2, and O2
• Molecules with an unequal distribution of
electrical charge are polar molecules.
• Water has a positive charge on one end
and a negative charge on the other.
Because of its uneven charge, water is a
polar molecule.
• A hydrogen bond is a weak chemical
attraction between polar molecules.
• Ionic bonds are formed by
the electrical attraction
between oppositely
charged ions.
• Ion is an atom that has
gained or lost an electron.
• An ion is a charged atom or
molecule.
Ionic Bonds, continued…
• An atom that has lost electrons is
positively charged.
• An atom that has gained electrons
is negatively charged.
Ions of opposite charges may
interact to form an ionic bond.
Example of an ionic bond:
Na+ + Cl-  NaCl
Sodium ion + Chlorine ion 
Sodium Chloride
Acids & Bases
pH is a measure of how acidic or
basic (alkaline) a solution is.
The
pH scale ranges from 0-14
and is used to measure pH.
• An acid is any substance
that forms hydrogen ions
(H+) in water.
• An acidic solution
contains more H+ ions.
• An acidic solution has a
pH < 7.
• A base is any substance
that forms hydroxide ions
(OH-) in water.
• A basic solution contains
fewer H+ ions than OHions.
• A basic solution has a
pH > 7.
• A pH of 7 indicates a neutral
between acidic and alkalinity.
Let’s test ourselves:
• 3.24
• 9.13
• 6.9
• 7.2
• 8.43
Water & Solutions
 Water
is an inorganic substance which
means it is not made from carbon or living
things.
 Water is composed of 1 atom of oxygen
and 2 atoms of hydrogen.
 Water molecules are linked by hydrogen
bonds.
 This causes water to heat up and cool
down slowly.
Water & Solutions
 Water,
which is essential for life,
stores heat efficiently and binds to
itself and other substances.
 The
most abundant inorganic
substance in a cell is water.
• The hydrogen bonds between
water molecules cause the
cohesion of liquid water.
• Cohesion is an attraction
between substances of the
same kind.
• Because of cohesion, water and
other liquids form drops and thin
films. The thin films allow some
insects to stand of the surface of
water because water is cohesive
and adhesive.
• This attraction between water
molecules (to itself) causes a
condition known as surface tension.
Surface Tension
• Water molecules are also
attracted to many other polar
substances.
• Adhesion is an attraction
between different substances.
Because water sticks to solids
(adhesion), water has the
property of capillarity.
• Capillarity is the ability to spread through
fine pores or to move upward through a
tubes (such as the stem of a plant)
against the force of gravity.
• The attraction of water to the walls of the
tube sucks the water up more strongly
than gravity pulls it down.
• Example: Graduated Cylinder, meniscus
Capillarity
Water dissolves many
substances…
 Due
to water’s polar nature (uneven
charge distribution), water makes a good
solvent, meaning that it can pull apart
other molecules.
 Nonpolar
molecules do not dissolve well in
water. When nonpolar substances, such as
oil are placed in water the oil forms lumps
of beads in the water.
Polar Molecules & Water
Nonpolar molecules & water
Chemistry of Cells
 Organic
compounds contain carbon.
 There
are 4 types of organic compounds
found in living things.
1.
2.
3.
4.
Carbohydrates
Lipids
Nucleic Acids
Proteins
• Without these compounds, cells
could not function.
• All of these compounds are long
repeating units called polymers.
• Polymers are large molecules formed
when many smaller molecules bond
together usually in long chains.
• Each subunit of a polymer is called a
monomer (simple molecule).
Carbohydrates
 Carbohydrates
are organic compounds
made of carbon, hydrogen, and oxygen
atoms in a 1:2:1 ratio.
 They are the main source of energy for
living things, and are found in most foods
– like fruits, vegetables, and grains.
 Most energy that is used in the human
body is stored as carbohydrates.
Carbohydrates
=
Three Types of Carbohydrates
1. Monosaccharides, or simple sugars, are
the building blocks of carbohydrates.
Examples of Monosaccharides:
• Glucose is manufactured by plants during
photosynthesis. It is the main source of
energy for plants and animals.
• Fructose is found in fruits and is sweet.
• They have the same molecular formula,
C6H12O6, but different structural formulas,
which makes them isomers.
Three Types of Carbohydrates
2. Disaccharides are two monosaccharide
molecules linked together.
Example:
Sucrose (table sugar) is composed of
fructose and glucose linked together.
Three Types of Carbohydrates
3. Polysaccharides are composed of many
monosaccharide subunits. Polysaccharides function
as storehouses of the energy contained in sugar.
Examples:
• Starch which is made by plants (like potatoes).
Energy is passed from potato to the person eating it
primarily by the energy stored in starch molecules.
• Glycogen which is made by animals. Both starch
and glycogen are made of hundreds of linked
glucose molecules.
• Cellulose is the polysaccharide that provides
structural support for plants. Humans cannot digest
cellulose (wood).
STARCH
GLYCOGEN IN LIVER CELLS
CELLULOSE
Lipids
 Lipids
are nonpolar molecules that are not soluble
in water.
 Lipids are used to store energy (long-term), for
insulation, and as protective coatings.
 Lipids are composed of 3 fatty acids bonded to a
glycerol molecule.
 Examples: fats, phospholipids, steroids, including
cholesterol and waxes.
FATS
STEROIDS
CHOLESTEROL
WAXES
Lipids
 The
monomers of lipids are fatty acids.
 Lipids are an important part of the structure
and functioning of cell membranes.
 Phospholipids make up the lipid bilayer of
cell membranes.
 Fats
are lipids that store energy.
 Saturated
Fats are solid at room temperature, and
they usually come from animals… butter
 Unsaturated Fats are liquid at room temperature,
and they usually come from plants like corn,
peanuts, and olives.
The phospholipid bilayer
Lipids
Waxes are highly waterproof.
 In
plants, wax forms a protective coating on the
outer surfaces, for example on the leaves.
 In animals, wax forms protective layers, for example
ear wax.
Nucleic Acids
 Nucleic
 The
Acids are in all of your cells.
building blocks of nucleic acids are
nucleotides.
 A nucleic acid is a long chain of smaller
molecules called nucleotides.
 A nucleotide has three parts:
1. Sugar
2. Base
3. Phosphate Group
Sugar
Phosphate Group
Base
Two Types of Nucleic Acids
1. DNA – Deoxyribonucleic Acid
DNA consists of 2 strands of nucleotides that spiral
around each other. The spiral-staircase shape of
DNA is known as the double helix. The two strands of
a DNA molecule are held together by hydrogen
bonds between the two bases across from one
another. Your chromosomes consist of very long
strands of DNA, which stores heredity information (or
genetic code) that can be used to make proteins.
2. RNA – Ribonucleic Acid
RNA consists of a single strand of nucleotides.
Proteins
 Proteins
are long chains of molecules called
amino acids that are linked together like parts on
a necklace.




Amino Acids are the building blocks of proteins.
There are 20 different Amino Acids, which bond to
each other by peptide bonds (covalent bonds
formed between amino acids).
Some proteins called enzymes regulate chemical
reactions in the body but remain unchanged by the
reaction.
The complete hydrolysis of a protein would result in
the formation of amino acids. Hydrolysis is a
chemical reaction which water is used to break
down a compound.
Proteins
 ATP
– Adenosine Triphosphate
ATP carries energy in cells.
ATP is a single nucleotide with two extra energystoring phosphate groups.