LEHNINGER PRINCIPLES OF BIOCHEMISTRY
DAVID CONCEPT REVIEW GUIDE 2026
GENETIC INFORMATION AND MOLECULAR
BIOLOGY BASICS
◉ cofactor. Answer: An inorganic ion or a coenzyme required for
enzyme activity.
◉ coenzyme. Answer: An organic cofactor required for the action of
certain enzymes; often has a vitamin component.
◉ prosthetic group. Answer: A metal ion or organic compound
(other than an amino acid) covalently bound to a protein and
essential in its activity.
◉ holoenzyme. Answer: A catalytically active enzyme, including all
necessary subunits, prosthetic groups, and cofactors.
◉ apoenzyme. Answer: The protein portion of an enzyme, exclusive
of any organic or inorganic cofactors or prosthetic groups that might
be required for catalytic activity.
, ◉ apoprotein. Answer: The protein portion of a protein, exclusive of
any organic or inorganic cofactors or prosthetic groups that might
be required for activity.
◉ active site. Answer: The region of an enzyme surface that binds
the substrate molecule and catalytically transforms it; also known as
the catalytic site.
◉ substrate. Answer: The specific compound acted upon by an
enzyme.
◉ ground state. Answer: The normal, stable form of an atom or
molecule, as distinct from the excited state.
◉ transition state. Answer: An activated form of a molecule in which
the molecule has undergone a partial chemical reaction; the highest
point on the reaction coordinate.
◉ activation energy (ΔG‡). Answer: The amount of energy (in joules)
required to convert all the molecules in 1 mol of a reacting
substance from the ground state to the transition state.
◉ reaction intermediate. Answer: Any chemical species in a reaction
pathway that has a finite chemical lifetime.
DAVID CONCEPT REVIEW GUIDE 2026
GENETIC INFORMATION AND MOLECULAR
BIOLOGY BASICS
◉ cofactor. Answer: An inorganic ion or a coenzyme required for
enzyme activity.
◉ coenzyme. Answer: An organic cofactor required for the action of
certain enzymes; often has a vitamin component.
◉ prosthetic group. Answer: A metal ion or organic compound
(other than an amino acid) covalently bound to a protein and
essential in its activity.
◉ holoenzyme. Answer: A catalytically active enzyme, including all
necessary subunits, prosthetic groups, and cofactors.
◉ apoenzyme. Answer: The protein portion of an enzyme, exclusive
of any organic or inorganic cofactors or prosthetic groups that might
be required for catalytic activity.
, ◉ apoprotein. Answer: The protein portion of a protein, exclusive of
any organic or inorganic cofactors or prosthetic groups that might
be required for activity.
◉ active site. Answer: The region of an enzyme surface that binds
the substrate molecule and catalytically transforms it; also known as
the catalytic site.
◉ substrate. Answer: The specific compound acted upon by an
enzyme.
◉ ground state. Answer: The normal, stable form of an atom or
molecule, as distinct from the excited state.
◉ transition state. Answer: An activated form of a molecule in which
the molecule has undergone a partial chemical reaction; the highest
point on the reaction coordinate.
◉ activation energy (ΔG‡). Answer: The amount of energy (in joules)
required to convert all the molecules in 1 mol of a reacting
substance from the ground state to the transition state.
◉ reaction intermediate. Answer: Any chemical species in a reaction
pathway that has a finite chemical lifetime.
