Basic Chemistry in Biology

1. Atoms: The Building Block of
Elements
• Elements are made up
of atoms. An atom is
the smallest particle of
an element that has the
properties of that
element. Atoms are
the basic building
blocks of all matter.

2. Structure of an Atom
• All atoms have the same
basic structure. The center
of the atom is the nucleus.
• They contain positively
charged particles called
protons (p+).
• Most nuclei contain
particles that have a
NEUTRAL charge called
neutrons (n0).

3. Structure of an Atom
• The region of space
surrounding the nucleus
contains extremely small,
negatively charged particles
called electrons (e-).

4. Compounds & Bonding
• A compound is a
substance that is
composed of two or more
different elements that are
chemically combined.

5. Covalent Bonds
• Covalent bonding occurs
when electrons are shared
between two atoms.

6. Molecules
• A molecule is a group of
atoms that are held
together by covalent
bonds.
• Each particle involved in
the molecule contributes
one or more electrons to
be shared by the atoms to
complete their outer
shells.

7. Ionic Bonds
• An atom can give up one or
more of its electrons,
resulting in a positively
charged ion.
• Another atom can gain
additional electrons,
resulting in a negatively
charged particle.
• The two oppositely charged
particles are attracted to one
another strongly, which
results in an ionic bond.

8. Mixtures & Solutions
A mixture is a combination
of elements in which the
individual components
retain their own properties.
Mixtures can be separated
easily by physical means,
such as mechanical
separation, filtration,
distillation, or
recrystallization.

9. Chemical Reactions
• Chemical reactions occur
when bonds are broken or
formed, causing substances to
recombine into different
substances.
• All of the different chemical
reactions that occur within an
organism are referred to as the
organism’s metabolism.
These reactions break down
and build molecules that are
important for the functioning
of organisms.

10. Mixtures & Solutions
• A solution is a
mixture in which one
or more substances are
distributed evenly in
another substance. In
other words, one
substance is dissolved
in another substance
and will not settle out
of solution.

11. Acids & Bases
• An acid is any substance
that forms hydrogen ions
(H+) in water. Acids have
a pH value that is less
than 7, which is
considered neutral.
• A base is any substance
that forms hydroxide
ions (OH-) when in
water. Bases have a pH
greater than 7.

12. Acids & Bases
• The pH scale is a
measure of how acidic
or basic something is.
The scale goes from 0
to 14 and the
numerical value is
obtained by taking the
log of the hydrogen
ion concentration.

13. Water & Its Importance
A polar molecule is one in
which the electrons are
shared, but they are shared
unequally. The electrons are
located closer to one atom
than another, resulting in
special properties.
Polar water molecules attract
ions as well as other polar
molecules. For this reason,
water is known as the
universal solvent, because
most substances will dissolve
in water.

14. Water & Its Importance
• Water atoms attract other
water molecules.
• The positively charged
hydrogen atom of one
water molecule attract
the negatively charged
oxygen atoms of another
molecule.

15. Water & Its Importance
• Because of its polarity,
water has the unique
property of being able
to creep up thin tubes.
Plants in particular
take care of this
property, called
capillary action.

16. Water & Its Importance
• Water has a very high specific
heat relative to most other
liquids. This means that a large
amount of energy is required to
raise the temperature of water
by a negligible amount. A large
amount of heat energy must be
lost to cause the temperature of
water to go down. This is very
important for cells, which exist
in an aqueous environment.
This property helps cells
maintain homeostasis.

17. Brownian Motion
• In 1827, Scottish scientist Robert
Brown observed pollen grains
suspended in water. He noticed
that the pollen moved constantly
in little jerks, like they were
being struck by some invisible
object. He found that the same
thing happened when he
observed particles of dye that
weren’t living. Brown was
observing evidence of Brownian
motion, the random movement of
atoms and molecules.

18. Diffusion
• Diffusion is the net
movement of particles
from an area of higher
concentration to an area of
lower concentration.
Diffusion is a slow
process because it depends
on the random movement
of atoms and molecules.
• Concentration,
temperature, and
pressure affect the rate of
diffusion.

19. Diffusion
• Concentration of the substances is
the primary controlling factor. The
more concentrated substances are,
the more rapidly diffusion occurs
because there are more collisions
between the particles of the
substances involved.
• An increase in temperature will
increase energy and causes more
rapid particle motion.
• Increasing pressure will accelerate
particle motion and, therefore,
diffusion.

20. Results of Diffusion
• Once two liquids
become evenly
distributed,
molecules continue
to move randomly
and collide with one
another; however,
no further change in
concentration will
occur.

21. Dynamic Equilibrium
• The continued random
movement of particles
with no overall
concentration change
is called dynamic
equilibrium.

22. Diffusion in Living Systems
• The difference in concentration
of a substance across space is
called a concentration
gradient.
• Because ions and molecules
diffuse from an area of higher
concentration to lower
concentration, they are said to
move with the gradient.
Diffusion will occur until the
concentrations are equal and no
further diffusion takes place.

23. The Structure of Carbohydrates
• A carbohydrate is a
biomolecule composed
of carbon, hydrogen,
and oxygen with a
ratio of two hydrogen
atoms and one oxygen
atom per one carbon
atom.
– CH2O

24. The Structure of Lipids
• Lipids are large
biomolecules that are made
mostly of carbon and
hydrogen with a small
amount of oxygen.
• Fats, oils, waxes, and
steroids are all lipids.
• They are insoluble in water
because their molecules are
nonpolar and are not
attracted to water molecules.

25. The Structure of Lipids
• A fatty acid is a long chain of
carbon and hydrogen.
• If each carbon in the chain is
bonded to other carbons by
single bonds, the fatty acid is
said to ‘saturated’.
• If a double bond is present in the
chain, the fatty acid is
unsaturated.
• Fatty acids with more than one
double bond are called
polyunsaturated.

26. The Structure of Lipids
Lipids are the major components of the
membranes that surround all
living cells.

27. The Structure of Proteins
• Proteins are essential to all life.
They provide structure for
tissues and organs and carry out
cell metabolism. A protein is a
large, complex polymer
composed of carbon, hydrogen,
oxygen, nitrogen, and
sometimes sulfur. The basic
building blocks of proteins are
called amino acids. There are
about 20 common amino acids
that combine in different ways
to make literally thousands of
proteins.

28. The Structure of Nucleic Acids
• Nucleic acids are complex
biomolecules that store cellular
information in the form of a
code. Nucleic acids are made
up of smaller subunits called
nucleotides. Nucleotides
consist of carbon, hydrogen,
oxygen, nitrogen, and
phosphorous atoms arranged in
three groups—a nitrogenous
base, a simple sugar, and a
phosphate group.

29. The Structure of Nucleic Acids
• The nucleic acid
deoxyribonucleic acid (DNA) is
the master copy of an organism’s
information code.
• The information coded in the
DNA contains the instructions
used to form all of the organism’s
enzymes and structural proteins.
Thus, DNA forms the genetic
code that determines how an
organism looks and acts.