CHAPTER 2 Highlights 43
Key Concepts
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Key Terms
Section 1
atom (28)
element (28)
compound (29)
molecule (29)
ion (30)Section 4
energy (38)
activation energy (39)
enzyme (40)
substrate (41)
active site (41)Section 2
cohesion (31)
adhesion (31)
solution (32)
acid (33)
base (33)Section 3
carbohydrate (34)
monosaccharide (34)
lipid (35)
protein (36)
amino acid (36)
nucleic acid (37)
nucleotide (37)
DNA (37)
RNA (37)
ATP (37)Nature of Matter
All matter is made of atoms. Atoms consist of electrons,
protons, and neutrons.
Molecules are groups of atoms linked by covalent bonds.
Hydrogen bonding occurs between polar molecules.
An ion is a charged atom or molecule. Ions of opposite
charge may form an ionic bond.Water and Solutions
Water, which is essential for life, stores heat efficiently
and binds to itself and other substances.
Water dissolves polar molecules and ionic compounds.
Acids increase the hydrogen ion concentration of
a solution.
Bases decrease the hydrogen ion concentration of
a solution.
The pH scale measures the strength of acids and bases.Chemistry of Cells
Organic compounds are found in living things.
Carbohydrates, such as glucose, are a source of energy
and are used as structural materials in organisms.
Lipids are nonpolar molecules that store energy and are
an important part of cell membranes.
Proteins are chains of amino acids. The sequence of
amino acids determines a protein’s shape and
specific function.
Nucleic acids store and transmit hereditary information.
ATP is the main energy currency of cells.Energy and Chemical Reactions
Chemical reactions absorb or release energy.
Starting a chemical reaction requires activation energy.
Enzymes speed up chemical reactions by decreasing
the activation energy of the reactions.
Enzymes bind only certain substrates.
Factors such as temperature and pH affect
enzyme activity.