Biology
Chapter 2
The Chemistry of Life
2.1 Learning Targets
• List the 3 subatomic particles that make up
atoms and list their charges
• Describe how isotopes of an element are
similar
• Name 4 uses of radioactive isotopes
• Distinguish between ionic & covalent
bonds
Section 2-1: Basic Chemistry
What is the basic unit of matter?
The Atom
What are the three subatomic particles?
1. Protons (p+) – (+) charge; weighs 1 amu
2. Neutrons (n0)– neutral charge (0); 1 amu
3. Electrons (e-)– (-) charge; 1/1840 amu
Section 2-1: Basic Chemistry
What subatomic particles are in the nucleus?
A. Protons & Neutrons
B. Overall charge of the nucleus is positive (+)
What subatomic particles are outside of the nucleus?
A. Electrons
B. Electrons are constantly moving within orbits known
as energy levels.
What is the charge of an atom?
Neutral because the number of protons equals the
number of electrons.
Basic Chemistry
What is an element?
Pure substance that is made of only one
kind of atom. Cannot be broken down or
converted to another substance.
Periodic Table Basics:
1. Atomic Number = # of p+; number of e2. Mass Number = number of p+ & n0
# of n0 = (mass #) – (atomic #)
Section 2-1: Basic Chemistry
What is an element?
Pure substance that is made of only one
kind of atom.
Periodic Table Basics:
1. Atomic Number = # of p+; number of e2. Mass Number = number of p+ & n0
# of n0 = (mass #) – (atomic #)
Section 2-1: Basic Chemistry
What is an isotope?
A. An atom of an element with an unusual
number of neutrons.
B. Isotopes are identified by their mass
numbers
C. Isotopes have the same chemical
properties because they have the normal
number of neutrons
Section 2-1: Basic Chemistry
These isotopes of carbon are named or identified
by their different MASS numbers. All isotopes of
carbon have the same atomic number.
Section 2-1: Basic Chemistry
What are radioactive isotopes?
Isotopes that have a nucleus that will decay
over time.
What are radioactive isotopes used for?
1. Dating rocks & fossils
2. Treat cancer
3. Kill bacteria in food
4. Used as a label or “tracer” to follow molecules
as they move through a cell.
Radioactive Isotope Uses in Medicine
This slide is not in the
student note packet.
Section 2-1: Basic Chemistry
What is a compound?
1. Substance formed by the chemical
combination of two or more elements in a
fixed ratio.
2. The physical & chemical properties of a
compound are different than the
elements that it is made from.
Section 2-1: Basic Chemistry
What are valence electrons?
1. e- found in the outer energy level of an
atom
2. They are used to form chemical
bonds.
Section 2-1: Basic Chemistry
What is an ionic bond?
1. Chemical bonds in which electrons are
transferred from one atom to another.
2. This makes one atom (+) and the other
atom (-).
3. These charged atoms are called ions,
and they are attracted to each other.
4. Ionic compounds dissolve in water.
Ionic Bonds
A sodium atom easily loses its one valence
electron and becomes a sodium ion (Na+).
This slide is not in the student note packet
Ionic Bonds
A chlorine atom easily gains an electron (from
sodium) and becomes a chloride ion (Cl-).
This slide is not in the student note packet
Ionic Bonds
These oppositely charged ions have a strong
attraction for each other, forming an ionic
bond.
This slide is not in the student note packet
Section 2-1: Basic Chemistry
What is a covalent bond?
1. Chemical bond in which e- are shared
between atoms.
2. e- are shared in pairs.
1 pair = single bond; 2 pair = double bond;
3 pair = triple bond
3. Compounds that have covalent bonds are
called molecules.
4. Very strong bond.
Section 2-1: Basic Chemistry
What are van der
Waals forces?
1. The weak attraction
between molecules
when they are close
together.
2. The feet of geckos
use these forces to
hang on to smooth
surfaces.
2.2 Learning Targets
• Compare acids & bases in terms of H+
concentration
• Describe differences between a solution &
a suspension using blood as an example
• Describe the purpose of buffers in living
organisms
Section 2-2: Chemistry of Water
What is cool about
H2O?
1. It is the most
abundant compound
in living things.
2. Most chemical
reactions occur in a
solution of H2O.
3. It expands when it
freezes.
Section 2-2: Chemistry of Water
What is polarity?
1. The unequal sharing of e- in a molecule.
2. The oxygen atom of H2O is an e- hog.
3. The oxygen end of the molecule has a partial
(-) charge & the hydrogen end has a partial (+)
charge.
4. All of the special properties of H2O are
related to its polarity.
Section 2-2: Chemistry of Water
What is a hydrogen bond?
1. It is the attraction
between the partial (+) of
one water molecule to
the partial (-) of another.
2. H2O can form 4 of these
at once.
3. Three dots represent a
H+ bond.
Section 2-2: Chemistry of Water
What is cohesion?
1. The attraction of
H2O molecules to
other H2O
molecules.
2. H+ bonds form
between the
molecules.
3. Surface tension is
caused by this.
Section 2-2: Chemistry of Water
What is adhesion?
1. The attraction of H2O
molecules to other
substances.
2. Hydrogen bonds are
formed between the H2O
and the substance.
3. Capillary action is
caused by this.
Section 2-2: Chemistry of Water
What is a mixture?
Two or more substances mixed together without
chemically combining.
What is a solution?
1. A mixture of substances in which something
is dissolved in H2O.
Solvent = does the dissolving
Solute = gets dissolved
2. H2O can dissolve both polar and ionic
compounds.
Section 2-2: Chemistry of Water
What is a suspension?
1. A mixture in H2O in
which the
substances do not
dissolve.
2. Anything that says
“shake well.”
3. Blood is a
suspension.
Section 2-2: Chemistry of Water
Dissociation of H2O:
H2O can break down to form ions.
What is an acid?
1. Any substance that forms H+ in solution
2. <7 on the pH scale
3. Strong acids have a pH of 1-3.
Section 2-2: Chemistry of Water
What is a base?
1. Any substance that forms OH- in solution.
2. >7 on the pH scale
3. Also called alkaline.
4. Strong bases have a pH of 11-14.
What is a buffer?
1. Substances that resist changes in pH.
2. Many are weak acids or bases.
3. Many proteins act as buffers.
Section 2-2: Chemistry of Water
What is the pH scale?
A measurement of the concentration of H+
in a solution. It is based on powers of 10.
Base: > 7 Neutral = 7 Acid: < 7
Buffers
The pH of the fluids within most cells in the human body
must generally be kept between 6.5 & 7.5 in order to
maintain homeostasis. If the pH is lower or higher, it
will affect the chemical reactions that take place
within the cells.
One of the ways that organisms control pH is through
dissolved compounds called buffers, which are weak
acids or bases that can react with strong acids or
bases to prevent sharp, sudden changes in pH.
Buffers
Adding acid to an unbuffered solution causes the pH of
the unbuffered solution to drop. If the solution contains
a buffer, however, adding the acid will cause only a
slight change in pH.
This slide is not in the student notes.
2.3 Learning Targets
• List the 4 major biomolecules/ organic macromolecules
• List the jobs of carbohydrates & identify their structural
monomers
• List the jobs of lipids & identify their structural monomers
• List the jobs of nucleic acids & identify their structural
monomers
• List the jobs of proteins & identify their structural
monomers
• Recognize & identify the 6 elements found in the basic
structure of monomers & polymers
Section 2-3: Biomolecules
What is organic chemistry?
The study of carbon
compounds.
What are carbon’s most
important traits?
1. Has 4 valence e-. This allows
carbon to make four covalent
bonds at once.
2. Carbon can bond with other
carbon atoms. This allows it
to form chains, rings, chains of
rings, or a combination of all.
Section 2-3 Biomolecules
What are the major elements of life? Present
in universe, Earth, and human body
Carbon, Hydrogen, Oxygen,
Phosphorous, Nitrogen, & Sulfur
Section 2-3: Biomolecules
What is a hydrocarbon?
The basic carbon compound. It is made of
only hydrogen and carbon.
Benzene
Methane
Section 2-3: Biomolecules
What are functional groups?
Compounds attached to carbon chains
to give them special properties.
Hydroxyl (-OH)
Amino (-NH2 or
Carboxyl
(-COOH or
)
)
Polar
Alcohols
Basic
Amino Acids
Acidic
Amino Acids
Fatty Acids
Section 2-3: Biomolecules
What is a macromolecule?
1. “Big” molecule; macro = big
2. Biomolecules are macromolecules
3. Made of individual subunits
What is the subunit of a macromolecule?
1. Monomer. Mono = one; mer = part
2. Dimer = two parts; 2 monomers joined together
3. Polymer = 3 or more parts; 3 or more
monomers
joined together; macromolecules are polymers
Section 2-3: Biomolecules
What is polymerization?
1. Chemical process in which monomers are
joined together to form dimers & polymers.
2. A.K.A. dehydration synthesis because
something is produced. Dehydration = take
away H2O; synthesis = to make. Take away
H2O to make something. Sometimes called
condensation.
3. It is an anabolic process because it takes
energy & builds new molecules.
4. Functional groups are used for this process.
Section 2-3: Biomolecules
What is hydrolysis?
1. Chemical process in which the bonds
between the monomers in a polymer are
broken.
2. A water molecule is used.
3. Hydro = H2O; lysis = to break; using
water to break something.
4. It is a catabolic reaction because energy
is released and molecules are broken.
Section 2-3: Biomolecules
What are the four biomolecules?
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
Section 2-3: Biomolecules
What is a carbohydrate?
1. Molecules that contain C, H, and O in a
1:2:1 ratio (glucose = C6H12O6)
2. Carbo = carbon; hydrate = H2O
What is the monomer of a carbohydrate?
1. Monosaccharide
2. Mono = one/single; saccharide = sugar; single
sugar
3. All sugars end with –ose (glucose, fructose,
lactose, sucrose, etc.).
Section 2-3: Biomolecules
What are disaccharides?
1. Two monosaccharides joined together.
2. This is done by polymerization.
3. Sucrose (table sugar) is an example.
Section 2-3: Biomolecules
What are polysaccharides?
1.. Three or more monosaccharides joined
together through polymerization.
2. Starch & cellulose are examples
Section 2-3: Biomolecules
What are the functions of carbohydrates?
1. Main source of energy for cells,
especially glucose.
2. Energy storage. Plants use starch;
animals use glycogen.
3. Structure. Plant cell walls are made of
cellulose, the exoskeletons of insects &
crabs are made of chitin.
Section 2-3: Biomolecules
What are lipids?
1. Compounds that contain C, H, and O,
but not in a 1:2:1 ratio.
2. They are oils, fats, waxes, & steroids.
3. None are soluble in H2O.
4. They have no real monomer.
5. A triglyceride is the form of a typical fat
or oil. Tri refers to 3 fatty acids; glyceride
refers to glycerol.
Section 2-3: Biomolecules
What is a saturated fatty acid?
1. The hydrocarbon chain only has single
bonds between the carbons (C-C).
2. It has the maximum amount of
Hydrogens (saturated w/H).
3. Tend to be solid at room temperature
(fats).
Section 2-3: Biomolecules
What is an unsaturated fatty acid?
1. The hydrocarbon chain has one double
bond between two carbons (C=C).
2. It has less than the maximum hydrogens.
What is a polyunsaturated fat?
1. The hydrocarbon chain has lots of C=C.
2. They tend to be liquid at room
temperature (oils).
Section 2-3: Biomolecules
What are the functions of lipids?
1. Energy storage – fats in animals
2. Main component of cell membranes
(phospholipids)
3. Chemical messengers (hormones).
Many steroids are hormones.
4. H2O proof coverings (waxes).
Section 2-3: Biomolecules
What are proteins?
1. Arguably the most important biomolecule.
2. Proteins usually end with –in (insulin,
hemoglobin, adrenalin, etc.)
Section 2-3: Biomolecules
What is the monomer of a protein?
Amino acid
What are the parts of an amino acid?
1. α-carbon (center carbon atom)
2. Carboxyl group (acid group)(-COOH)
3. Amino group (-NH2)
4. Hydrogen atom (H)
5. R group; this is a variable; there are 20
different R groups; 20 different amino acids
Section 2-3: Biomolecules
How are amino acids joined together?
1. By a peptide bond formed through
polymerization.
2. The amino group of one amino acid is
connected to the carboxyl group of
another.
Section 2-3: Biomolecules
What is a dipeptide?
Two amino acids joined together.
What is a polypeptide?
Three or more amino acids joined
together. Most proteins are polypeptides
made of at least 300 amino acids.
What determines a protein’s function?
Its shape/structure.
Section 2-3: Biomolecules
What are the levels of protein structure?
1. Primary (1o) – amino acid sequence; this
determines the next 3 levels
2. Secondary (2o) – the amino acid chains coils
and folds
3. Tertiary (3o) – the 2o structure folds on itself
4. Quaternary (4o) – one or more polypeptide
chains are added; a.k.a. globular protein;
hemoglobin is an example.
Section 2-3: Biomolecules
What are the functions of proteins?
1. Energy source – after carbs & lipids have been used.
2. Structure – microtubules & microfilaments give shape
to cells.
3. Movement – actin & myosin are used in muscle
contraction.
4. Transport – hemoglobin transports O2
5. Chemical messengers – many hormones are
proteins (insulin)
6. Immunity – antibodies are proteins
7. Enzymes – these proteins regulate chemical
reactions; this is the most important function of
proteins.
Section 2-3: Biomolecules
What are nucleic acids?
1. Compounds that contains C, H, O, N, &
P.
2. Involved with heredity (DNA)
3. Involved with protein synthesis (DNA
& RNA)
4. Involved with energy use (ATP)
Section 2-3: Biomolecules
What is the monomer of a nucleic acid?
Nucleotide
What are the parts of a nucleotide?
1. 5-carbon sugar (either ribose or
deoxyribose)
2. Phosphate group
3. Nitrogenous base (5 different kinds of
these)
Section 2-3: Biomolecules
Basic Nucleotide Structure:
ATP Structure:
2.4 Learning Targets
• Explain what factors influence enzyme
activity & the affect of those factors on the
enzymes
• Describe the role of energy in chemical
reactions & the significance of enzymes in
biological reactions
Section 2-4: Chemical Reactions &Enzymes
What is a chemical reaction?
1. Process that changes one set of chemicals
into another set of chemicals.
2. Always involves breaking bonds in the
reactants & forming new ones in the
products.
A+BC+D
Reactants (left of the arrow)
Products (right of the arrow)
The arrow means “yields.”
Section 2-4: Chemical Reactions &Enzymes
What is activation energy (EA)?
Energy required to get a chemical reaction
started.
What is an anabolic reaction?
1. Absorbs energy; endergonic.
2. The energy is used to make new bonds.
3. Dehydration synthesis is an anabolic reaction.
4. New molecules are built.
Section 2-4: Chemical Reactions & Enzymes
What is a catabolic reaction?
1. Releases energy; exergonic
2. Energy is released because bonds &
molecules are broken.
3. Hydrolysis is a catabolic reaction.
Section 2-4: Chemical Reactions &Enzymes
What is an enzyme?
1. Proteins that speed up reaction rates by
lowering the EA.
2. Enzymes are catalysts; they are not used
up during the reaction.
3. They are very specific; one enzyme per
reaction.
4. Enzymes end with –ase.
Section 2-4: Chemicla Reacitons & Enzymes
Lock & Key Model of Enzyme Function:
1. Substrate = reactant
2. Active site = place on
the enzyme where the
work occurs. It is
substrate specific.
3. Enzyme-Substrate
complex last for a
very short time.
Section 2-4: Chemical Reactions & Enzymes
How do you control enzymes?
1. Changes in pH
2. Changes in temperature; especially
higher temperature
3. Chemical regulators – these block the
active sites.
Changes in pH & high temps changes
the shape of the enzyme (denature).