LEHNINGER PRINCIPLES OF BIOCHEMISTRY
2026 ASSESSMENT SCRIPT QUESTION BANK
DETAILED RESPONSES
◉ specificity.
Answer: The ability of an enzyme or receptor to discriminate among
competing substrates or ligands.
◉ cooperativity.
Answer: The characteristic of an enzyme or other protein in which
binding of the first molecule of a ligand changes the affinity for the
second molecule. In positive cooperativity, the affinity for the second
ligand molecule increases; in negative cooperativity, it decreases.
◉ amplification.
Answer: The action of making something more marked or intense.
◉ enzyme cascade.
Answer: A series of reactions, often involved in regulatory events, in
which one enzyme activates another (often by phosphorylation),
which activates a third, and so on. The effect of a catalyst activating a
catalyst is a large amplification of the signal that initiated the
cascade.
,◉ modularity.
Answer: The degree to which a system's components may be
separated and recombined, often with the benefit of flexibility and
variety in use.
◉ scaffold proteins.
Answer: Noncatalytic proteins that nucleate formation of
multienzyme complexes by providing two or more specific binding
sites for those proteins.
◉ desensitization.
Answer: A universal process by which sensory mechanisms cease to
respond after prolonged exposure to the specific stimulus they
detect.
◉ integration.
Answer: The coordination of processes in a system.
◉ response localization.
Answer: The process of making a biochemical response local in
character or restricting it to a particular place.
◉ G protein-coupled receptors (GPCRs).
, Answer: A large family of membrane receptor proteins with seven
transmembrane helical segments, often associating with G proteins
to transduce an extracellular signal into a change in cellular
metabolism.
◉ guanosine nucleotide-binding proteins.
Answer: A large family of GTP-binding proteins that act in
intracellular signaling pathways and in membrane trafficking. Active
when GTP is bound, they self-inactivate by converting GTP to GDP.
Also called G proteins.
◉ G proteins.
Answer: A large family of GTP-binding proteins that act in
intracellular signaling pathways and in membrane trafficking. Active
when GTP is bound, they self-inactivate by converting GTP to GDP.
Also called guanosine nucleotide-binding proteins.
◉ second messenger.
Answer: An effector molecule synthesized in a cell in response to an
external signal (first messenger) such as a hormone.
◉ agonist.
Answer: A compound, typically a hormone or neurotransmitter, that
elicits a physiological response when it binds to its specific receptor.
2026 ASSESSMENT SCRIPT QUESTION BANK
DETAILED RESPONSES
◉ specificity.
Answer: The ability of an enzyme or receptor to discriminate among
competing substrates or ligands.
◉ cooperativity.
Answer: The characteristic of an enzyme or other protein in which
binding of the first molecule of a ligand changes the affinity for the
second molecule. In positive cooperativity, the affinity for the second
ligand molecule increases; in negative cooperativity, it decreases.
◉ amplification.
Answer: The action of making something more marked or intense.
◉ enzyme cascade.
Answer: A series of reactions, often involved in regulatory events, in
which one enzyme activates another (often by phosphorylation),
which activates a third, and so on. The effect of a catalyst activating a
catalyst is a large amplification of the signal that initiated the
cascade.
,◉ modularity.
Answer: The degree to which a system's components may be
separated and recombined, often with the benefit of flexibility and
variety in use.
◉ scaffold proteins.
Answer: Noncatalytic proteins that nucleate formation of
multienzyme complexes by providing two or more specific binding
sites for those proteins.
◉ desensitization.
Answer: A universal process by which sensory mechanisms cease to
respond after prolonged exposure to the specific stimulus they
detect.
◉ integration.
Answer: The coordination of processes in a system.
◉ response localization.
Answer: The process of making a biochemical response local in
character or restricting it to a particular place.
◉ G protein-coupled receptors (GPCRs).
, Answer: A large family of membrane receptor proteins with seven
transmembrane helical segments, often associating with G proteins
to transduce an extracellular signal into a change in cellular
metabolism.
◉ guanosine nucleotide-binding proteins.
Answer: A large family of GTP-binding proteins that act in
intracellular signaling pathways and in membrane trafficking. Active
when GTP is bound, they self-inactivate by converting GTP to GDP.
Also called G proteins.
◉ G proteins.
Answer: A large family of GTP-binding proteins that act in
intracellular signaling pathways and in membrane trafficking. Active
when GTP is bound, they self-inactivate by converting GTP to GDP.
Also called guanosine nucleotide-binding proteins.
◉ second messenger.
Answer: An effector molecule synthesized in a cell in response to an
external signal (first messenger) such as a hormone.
◉ agonist.
Answer: A compound, typically a hormone or neurotransmitter, that
elicits a physiological response when it binds to its specific receptor.
