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 Everything
that happens in a living
organism involves chemical reactions
 Death occurs when these chemical
reactions can no longer occur
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Chapter 2
 Elements
are made of a single kind of
atom and cannot be broken down by
chemical means into simpler
substances.
 Atoms
are composed of protons,
neutrons, and electrons.
 Six
elements (C, H, N, O, P, and S) are
commonly found in living things.
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Chapter 2


Section 1 Composition of Matter
Isotopes
• Atoms of the same element that
have a different number of
neutrons are called isotopes.
• A neutron has no charge, so
there is no change in charge
• A neutron has mass, so the
mass of an isotope is different
Since Isotopes have the same
number of electrons, all isotopes
of an element will have the same
properties of an element
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+
C-12 = _____ p and _____ n
0
+
0
C-13 = _____ p and _____ n
+
0
C-14 = _____ p and _____ n
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
Radioactive or unstable isotopes due to an imbalance
in the # of protons & neutrons.

What are some biological uses of radioisotopes?
a) Cellular tracers – Tract the movement of
molecules
 b) Medical testing – Brain scan, blocked arteries
and intestines.
 c) Biochemical analysis of blood or urine
(hormones, drugs, antigens).
 d) Medical treatments- treating cancer

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Chapter 2
Section 1 Composition of Matter
Compounds, continued
• Covalent Bonds
– A covalent bond
is formed when
two atoms share
electrons.
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Compounds, continued
• Ionic Bonds
– An ionic bond is formed when one atom
gives up an electron to another. The
positive ion is then attracted to a
negative ion to form the ionic bond.
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
A chemical formula indicates the number
of atoms in each substance; H2O contains
3 atoms (2 hydrogen and 1 oxygen)
•
Subscript indicates the number of
atoms
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 Matter
is never created nor destroyed,
only changed from one form to another
Or
 In a chemical reaction, the mass of the
reactants is always equal to the mass of
the products
So
• A chemical equation always has to be balanced; the
same number of each type of atom is on both sides.
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• All chemical equations have three main
parts
 Reactants on the left side of the arrow
 Arrow that is read as “yields”
 Products are on the right side of the arrow
• Coefficient indicates the number of
molecules; 6H2O is six molecules of water
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 Na
+ Cl2  NaCl
 H2
+ O2  H2O
 Zn
+ HCl  Zn2Cl + H2
 HgO
 Hg + O2
 C6H12O6
+ O2  H2O + CO2
• And Name the process this equation
represents!
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Energy in living things
• Energy is stored in chemical
compounds, and released when
compounds are broken down and new
ones are made from the existing
atoms.
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

Energy in the bonds of chemical formulas represents
potential energy
• Plants store energy in a compound with many bonds,
called starch
• Animals store energy in a similar compound, called
glycogen
• Energy is transferred throughout all living things in a
molecule called adenosine triphosphate, or ATP
Kinetic energy in living organisms occurs as chemical
reactions occur, allowing for all the processes of living things
to occur
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Energy Currency
• Adenosine triphosphate (ATP) stores and releases
energy during cell processes, enabling organisms
to function.
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Chapter 2
Energy and Chemical Reactions,
continued
• Activation Energy
– Enzymes lower the amount of
activation energy necessary for a
reaction to begin in living systems.
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Chapter 2
Section 2 Energy
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 Acts
as a buffer for body temperature
 Provides soluble environment for chemical
reactions
 Serves as a reactant in chemical reactions
 Provides hydration that maintains cell
turgidity
 Maintains protein shape
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Chapter 2
Section 3 Water and Solutions
Polarity
• Water is considered to be a polar
molecule due to an uneven
distribution of charge.
• The electrons in a water molecule are
shared unevenly between hydrogen
and oxygen.
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Chapter 2
Section 3 Water and Solutions
Polarity, continued
• Solubility of Water
– The polarity of water makes it
effective at dissolving other polar
substances such as sugars, ionic
compounds, and some proteins.
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Chapter 2
Section 3 Water and Solutions
Hydrogen Bonding
• A hydrogen bond is
the force of
attraction between a
hydrogen molecule
with a partial
positive charge and
another atom or
molecule with a
partial or full
negative charge.
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Chapter 2
Section 3 Water and Solutions
Hydrogen Bonding, continued
• Temperature Moderation
– Water has the ability to absorb a relatively
large amount of energy as heat
– This property is called specific heat, the
amount of heat needed to raise the
temperature of 1 gram of a material by 1
degree Celsius
– and the ability to cool surfaces through
evaporation.
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Chapter 2
Section 3 Water and Solutions
Acids and Bases
• Ionization of Water
– Water ionizes into hydronium ions (H3O+)
and hydroxide ions (OH–).
• Acids
– Acidic solutions contain more hydronium
ions than hydroxide ions. 1-6.9
• Bases
– Basic solutions contain more hydroxide
ions than hydronium ions. 7.1-14
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Chapter 2
Section 3 Water and Solutions
Acids and Bases, continued
• pH
– Scientists have developed a scale for comparing
the relative concentrations of hydronium ions
and hydroxide ions in a solution. This scale is
called the pH scale, and it ranges from 0 to 14.
– pH of 7 is neutral
• Buffers
– Buffers are chemicals that neutralize the effects
of adding small amounts of either an acid or a
base to a solution.
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





During exercise, muscles use up oxygen as they
convert chemical energy in glucose to mechanical
energy.
This causes chemical changes in the blood, which
causes the pH of the blood to drop.
If the pH of the body gets too low (below 7.4), a
condition known as acidosis results.
Ideal blood pH is 7.4.
If the pH drops below 6.8 or rises above 7.8, death may
occur.
Buffers in the blood protect against large changes in
pH.
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Chapter 2
Section 3 Water and Solutions
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Molecular
Modeling
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Chapter 3
Section 1 Carbon Compounds
 Organic
compounds contain carbon
atoms and are found in living things.
 Most inorganic compounds do not
contain carbon atoms.
 Carbon atoms can readily form four
covalent bonds with other atoms
including other carbon atoms. The
carbon bonds allow the carbon atoms
to form a wide variety of simple and
complex organic compounds.
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Chapter 3
Section 1 Carbon Compounds
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Chapter 3
Section 1 Carbon Compounds
Functional Groups
• Functional groups are groups of atoms
that influence the properties of molecules
and the chemical reactions in which the
molecules participate.
• YOU MUST BE ABLE TO PICK
THESE FOUR OUT ON A
TEST
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 Large
molecules formed by
polymerization, the process of small
monomers or subunits joining together to
form large macromolecules
• Be sure you know the monomer that makes up
each group of macromolecule!
 Four
major groups of macromolecules
found in living things
• Carbohydrates
• Lipids
• Nucleic acids
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Chapter 3
Section 1 Carbon Compounds
Macromolecules, continued
• Condensation reactions join monomers (small simple
molecules) to form polymers. A condensation reaction
releases water as a by-product.
• A condensation reaction is a type of synthesis
reaction; it is also called dehydration synthesis
A+BC
(in this case a small amount of water is also produced)
• In a hydrolysis reaction, water is used to split
polymers into monomers.
• A hydrolysis reaction is a form of decomposition
reaction
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CA
+ Bmenu
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Chapter 3
Section 2 Molecules of Life
Carbohydrates
• Carbohydrates are organic compounds
composed of carbon, hydrogen, and
oxygen in a ratio of about one carbon to
two hydrogen atoms to one oxygen atom.
• Carbohydrates are a source of energy and
are used as structural materials in
organisms.
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Chapter 3
Section 2 Molecules of Life
Carbohydrates, continued
• Monosaccharides
– Carbohydrates are made up of monomers
called monosaccharides.
• Disaccharides and Polysaccharides
– Two monosaccharides join to form a
double sugar called a disaccharide.
– A complex sugar, or polysaccharide, is
made of three or more monosaccharides.
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Chapter 3
Section 2 Molecules of Life
Proteins
• Proteins are organic compounds composed mainly
of carbon, hydrogen, oxygen, and nitrogen.
• Proteins have many functions including structural,
defensive, and catalytic roles.
• Amino Acids
– Proteins are made up of monomers called amino
acids.
– The sequence of amino acids determines a
protein’s shape and function.
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Chapter 3
Section 2 Molecules of Life
Proteins, continued
• Dipeptides and Polypeptides
– Two amino acids are joined by peptide
bonds to form a dipeptide.
– A long chain of amino acids is called a
polypeptide.
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Chapter 3
Section 2 Molecules of Life
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Chapter 3
Section 2 Molecules of Life
Proteins, continued
• Enzymes
– Enzymes speed up chemical
reactions and bind to specific
substrates.
– The binding of a substrate with an
enzyme causes a change in the
enzyme’s shape and reduces the
activation energy of the reaction.
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Chapter 3
Section 2 Molecules of Life
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Chapter 3
Section 2 Molecules of Life
Lipids
• Lipids are nonpolar molecules that store
energy and are an important part of cell
membranes. Because lipids are nonpolar,
they are all insoluble in water.
• Fatty Acids
– Most lipids contain fatty acids,
unbranched carbon molecules that
have a hydrophilic end and a
hydrophobic end.
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Chapter 3
Section 2 Molecules of Life
Lipids, continued
• Triglycerides
– Triglycerides consist of three fatty acids
and one molecule of glycerol.
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Chapter 3
Section 2 Molecules of Life
Lipids, continued
• Phospholipids
– Phospholipids, which make up cell
membranes, consist of two fatty
acids and one glycerol molecule.
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Chapter 3
Section 2 Molecules of Life
Lipids, continued
• Waxes
– A wax is made of one long fatty acid
chain joined to one long alcohol.
• Steroids
– A steroid is composed of four fused
carbon rings.
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Chapter 3
Section 2 Molecules of Life
Nucleic Acids
• A nucleic acid is a large and complex
organic molecule that stores and
transports information.
• Consists of subunits of nucleotides
• 3 parts of a nucleotide
• Nitrogen containing base
• Phosphate
• 5 carbon sugar
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Chapter 3
Section 2 Molecules of Life
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Chapter 3
Section 2 Molecules of Life
Nucleic Acids, continued
• The nucleic acid deoxyribonucleic acid
(DNA) contains genetic information for cell
activities.
• Ribonucleic acid (RNA) molecules play
many key roles in building of proteins and
can act as enzymes.
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